Grasshopper - Vegetation Relationships on Montana Grasslands
by NORMAN LEWIS ANDERSON
A thesis submitted to the Graduate Faculty in partial fulfillment of the requirements for the degree of
DOCTOR OF PHILOSOPHY in Entomology
Montana State University
© Copyright by NORMAN LEWIS ANDERSON (1962)
Abstract:
The general distribution of 65 grasshopper species on Montana grasslands east of the Rocky Mountains
is recorded. This distribution is discussed primarily from the standpoint of known food-plant
preferences of grasshopper species involved. The results of detailed investigations of
grasshopper-vegetation relationships on 105 native grassland and abandoned field study sites are
presented and discussed. It was concluded that vegetation plays an important role in the selection of
areas of occupancy by grasshoppers within a grassland habitat but is not a causative agent responsible
for initial changes in grasshopper abundance. GRASSHOPPER - VEGETATION RELATIONSHIPS ON MONTANA GRASSLANDS
by
NORMAN LEWIS ANDERSON, JR.
A thesis submitted to the Graduate Faculty in partial
fulfillment of the requirements for the degree
of
DOCTOR OF PHILOSOPHY
in
Entomology
Approved:
. I X/'/
^
Heady Major Department
Chairman, EyaAining Committee
D e a n , Graduate/Division
MONTANA STATE COLLEGE
Bozeman, Montana
June, 1962
ACKNOWLEDGMENT
The writer is deeply grateful to Doctor J 9 H. Pepper,
Head,' and Professor E 9 B 9 Hastings of the Department of
Zoology and Entomology, Montana State College, for their
stimulating discussions, interest, and encouragement during
all phases of the investigation.
Sincere thanks are extended
to Doctors Wo E 9 Booth, J 9 H 9 Rumely, and J 9 C . Wright,
Department of Botany and Bacteriology, Montana State College,
for help in plant identification and for field aid in making
various vegetation measurements.
iv
TABLE OF CONTENTS
LIST OF TABLES
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LIST OF FIGURES... ......................................
ABSTRACT
0 0 0 0 0 9 0 0 0 0 0
INTRODUCTION o
0 0 0 9 0 0 9 9 0 0 0 0 0 0 0 9 0 9 9 0 0 0 0 0 0 0 0 9 0 0 9 9 0 0 0 0 0
vii
.viii
o e o o o o o o o o e d o o o e o o c o o o o o o e o o e o e e o o o o e o o o o e o o o
METHODS OF STUDY...
I
0 0 0 0 0 9 0 0 0 0 0 0 0 , 0 0 0 0 0 0 0 0 0 0 0 9 0 0 0 0 0 0 0 0 0 0 0 9 0 0
GRASSHOPPER SPECIES DISTRIBUTION.
0 0 0 0 0 0 0 0 9 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
Acrolophitus hirtipes- (Say)..... ..
Aeloplus -turnbulli turnbulli (Thomas)
Aerochoreutes carlinianus carlinianus (Thomas)
Aerbpedellus clavatus (Thomas)
Ageneotettix deorum TScudder).
Amphitornus coloradus (Thomas).
Arphia conspersa Scudder
Arphia pseudonietana pseudonietana (Thomas)
Aulocara elliotti (Thomas)
Boopedon nubiIum'(Say).
Brachystola magna (Girard) o o o o o o o o o o o o o
Bradynotes obesa (Thomas)
Bruneria brunnea (Thomas)
Bruneria sordida (McNeill)
Camnula pellucida (Scudder)
Ghorthippus longicornis (Latreille).
Chortophaga viridifasciata (De Geer)
Circotettix rabula rabula Rehn and Hebard
CordlIlacris crenulata (Bruner)
Cratypedes negle'ctus (Thomas)
Dactylotum picturn TThomas)
Derotmema haydenii haydenii (Thomas)
Dissosteira Carolina (Linnaeus)
Drepanopterna femoraturn (Scudder)
Encoptolophus sordidus costalis (Scudder)
Eritettix simplex tricarinatus (Thomas)
Hadrotettix trifasciatus (Say)
Hespefotettix viridis pratensis (Scudder)
Hlppiscus rugosus (Seudder)
Hypochlora alba (Dodge)
MeIanoplus alpinus (Scudder)
Melanoplus bilituratus (W
a
l
k
e
r
.
Melanoplus bivittatus (Say)...................
Melanoplus bowditehi eanus (Hebard)
Melanoplus bruneri (Scudder)
0 0 0 0 0 0 0 0 0 0 0 0 9 0 0 0 '
0 0 0 0 0 0 0 0 9 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0 0 0 0 0 9 0 0 0 0
0 0 0 0 0 0 9 0 0 0 0 0 9
0 0 0 0 0 0 0 0 0 0
0-00099
0 0 0 0 0 0 0 0 0 0 0 9 0 0
O O O O O O
0 0 0 0 0 0 0 9 0 0 0 0 0 0
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O O O O O .
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0
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0
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0
0
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0
19
20
20
21
21
21
22
22
23
O O O O O O
0 0 0 0 0 0 0 9 0 0
0 0 0 0 0 9 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 9 0 0 0 9
0 0 0 0 0 0 0 0 0 0 0 0 0 9 0
0
0
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0
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9
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0
0
0 0 0 0 0 0 0 0 0 0 0 9 0 0 0 0
0 0 0 0 0 0 0 0 9 0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0 0 0 9 9 0 0 0 0 0
0 00
0 0 0 0 0 0 0 0 0 0 0 0 9 0 9 0 0 0
0 0 0 9 0 9 0 0 0 0 0
0
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9
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12
12
13
13
14
14
15
15
15
16
17
17
IS
IS
IS
0 0 0 0 0 0 0 0 9 0 0 0
0
12
23
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23
24
24
25
25
25
26
27
27
27
Y
Melanoplus confU.SU.S (S c"u.dd6ir)« » •»
Melanoplus dctwsOXii (Scu.dd.03r) @000*000****00*0*00
Melanoplus differentialis (Thomas
.........
Melanoplus femur-rubrum femur-rubruim (Be Geer)......
Melanoplus Kladstoni (Scudder)..........
Melanoplus infantilis (Scudder)................•....
Melanoplus keeleri luridus (
D
o
d
g
e
)
•
Melanoplus kennicotti (Scudder
Melanoplus montanus (T
h
o
m
a
s
Melanoplus occidentalis occidentalis (Thomas)......
Melanoplus oregonensis (Thomas)...............
Melanoplus
__________ packardii (Scudder)................
Mermiria maculipennis macelungi (Rehn)...............
Metator pardalinus (Saussure)............
Neopodismopsis abdominalis (Thomas).. =...........
Opei a -0bsoura (Thomas)..............................
Orphulella pelidna pelidna (Burmeister).............
Orphulella speciosa (Scudder)......................
Phlibostroma quadrimaculatum (Thomas)...............
Phoetaliotes nebrascensis (
T
h
o
m
a
s
Pseudopomala brachyptera ( S c u d d e r .
Psoloessa delicatula delicatula (Scudder)...........
Schistocerea lineata (Scudder)......................
Spharagemon collare (Scudder).......................
Spharagemon equals (Say)
......
Trachyrhachys kiowa kiowa (T
h
o
m
a
s
Trimerotropis bruneri (McNeill)...........
Trimerotropis campestris (McNeill)..................
Trimerbtropis cincta (
T
h
o
m
a
s
Ianthippus corallipes (Haldeman)....................
o
)
ADDITIONAL RESULTS AND DISCUSSION
SUMMARY
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LITERATURE CITED.....
.
»
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
2S
2^
29
30
30
30
31
31
32
32
32
33
33
34
34
33
35
36
36
37
38
38
39
39
40
41
41
41
42
42
43
66
63
LIST OF TABLES
TABLE I
A summary of study site vegetation measurements
TABLE II
Per cent frequency of occurrence of grasshopper
species in numbers greater than I per sq yd on
Native Grassland Study Sites.
(Perennial Grass-Cover Classes)....
TABLE III
Per cent frequency of occurrence of grasshopper
species in numbers greater than I per sq yd on
Abandoned.Field Study Sites.
(Perennial Grass-Cover. Classes)....
TABLE IV,
Per cent frequency of occurrence of grasshopper
species in numbers greater than I per sq yd on
Native Grassland Study Sites.
(Total Foliage-Cover Classes)......
TABLE V
Per cent frequency of occurrence of grasshopper
species in numbers greater than I per sq yd on
Abandoned Field Study Sites.
(Total Foliage-Cover Classes).......
TABLE VI
Per cent frequency of occurrence of grasshopper
species in numbers greater than I per sq yd on
Native Grassland Study Sites.
(Litter-Cover Classes)..... .
TABLE VII
Per cent frequency of occurrence of grasshopper
■ species in numbers greater than I per sq yd on
Abandoned Field Study Sites.
(Litter-Cover Classes
TABLE VIII
Vegetation on 4 permanent square-meter quadrats
at the OW Ranch, Decker, Montana..............
- vii
LIST OF FIGURES
1
FIGURE I.
Study Site Locations
FIGURE 2.
Vegetative Types.......... ...................... 5
FIGURE 3 *
Seasonal Fluctuations in the Grasshopper
Population of One Area As'Measured in 1958...... 45
>
...... ....................4
viii.-
ABSTRACT
The general distribution of 65 grasshopper species on
Montana grasslands east of the Rocky Mountains is recorded.
This distribution is discussed primarily from the standpoint
of known food-plant preferences of grasshopper species
involved. The results of detailed investigations of grass­
hopper-vegetation relationships on 105 native grassland and
abandoned field study sites are presented and discussed. It
was concluded that vegetation plays an important role in the
selection of areas of occupancy by grasshoppers within a
grassland habitat but is not a causative agent responsible for
initial changes in grasshopper abundance.
I
INTRODUCTION
The history of grasshoppers on grasslands is largely one
of fluctuating numbers.
In a particular area the appearance
of these, insects in low numbers for a period is followed occa­
sionally by an extreme increase in the population density.
When such increases in several localities coincide the desig­
nation "grasshopper outbreak" is often assigned to the total
area.
Even during these periods, however, there are areas
within such a region in which populations remain.low.
As yet,
such population fluctuations are not predictable as to time or
.location.
One of the environmental factors which appears to be of
importance in influencing grasshopper distribution and numbers
is vegetation, but critical understanding of grasshoppervegetation interrelationships is not fully revealed in the
literature.
For example, there are differing opinions con­
cerning the importance of vegetation composition from the
standpoint of food. Morse (1899) stated that grasshoppers
"...are voracious, their food being general in character
rather than special, a question of quantity rather than qual­
ity."
Since that time, however, food-plant preferences have
been recognized and Isely (1938) found that, under cage condi­
tions, those species which are selective feeders will starve
if they are deprived of their host-plants even in the presence
of abundant fresh vegetation, palatable to other grasshopper
2
species.
On the other hand, Williams (1954) found that
"...when grasshoppers were deprived of water as well as food
for 4& hours, they could be induced to feed on a number of
succulent plants which previously they would only slightly
nibble."
Other workers (Clark 1947a, Rubtzov 1934, Strohecker
1937, Urquhart 1941) have generally concluded that particular
food-plants are not limiting and that other environmental
factors such as the amount of green feed and cover, micro­
climatic conditions, sunlight, moisture, and rate of evapo­
ration are more important.
On grassland areas of Russia, workers (Bei-Bienko 1930,
Nefedov 1931, Rubtzov 1932, 1934) have found direct correla­
tions between the abundance of certain grasshopper species and
the taxonomic constitution and amount of plant cover.
Kachaeva Sc Rubtzov (1935) state that "...in different habitats
a decrease in the number of species and an increase in numbers
of individuals of grasshoppers were parallel to a decrease in
the number of species in plant associations and in the per- .
centage of plant cover."
In England, Clark (1940) found that:
"Height and density
of the vegetation are probably the most important features for
grasshoppers."
Australia:
On the other hand, Clark (1947) found that in
"The amounts of shelter vegetation and green feed
are of greater importance than the amount of bare ground (or
total plant cover)...".
In this case, "shelter height", as
- 3 distinguished from absolute plant height was defined as "
the height of that part of a single plant or aggregate which
cast practically unbroken shade on the ground."
The main objectives of the study reported here were two­
fold:
(i) to determine the distribution of grasshoppers on
the grasslands of Montana east of the Rocky Mountains, and
(ii.) to learn something of the role vegetation may play in
determining grasshopper distribution and numbers.
METHODS OF STUDY
Study sites were located within specific grassland areas
east of the Rocky Mountains (Fig. I).
At the start of the
study it was believed that a general map of vegetation types,
such as that of He!burn, Edie, & Lightfoot (1962) (Fig. 2),
would suffice in the selection of areas for detailed study.
It was found upon using this map that a number of distinctive
grassland communities existed within each of the broad vegeta­
tion-type categories used.
It was felt that these commu­
nities differed enough from one another to warrant independent
consideration from the standpoint of grasshopper-vegetation
relationships.
Consequently, soil survey and geological for­
mation maps were consulted extensively in selecting as many
different soil types and resultant grassland communities for
study as possible.
Thirteen grassland community types,
including abandoned fields, were subsequently recognized.
fig
I STUDY
SITE
LOCATIONS
SOURCE
Vegetative Rangeland Types In Montana,
Montana Agricultural Experim ent Station,
Bozeman, Montana, 1949.
fig 2. VEGETATION
TY PES
(FROM://£!BURN, ED/E, 8 UGHTFOOT, 1962)
With the exception of abandoned fields, these vegetation types
were recognized primarily on the basis of the .dominant species
present.
A detailed vegetation analysis and description of
these types and the study sites within them is the subject of
a forthcoming paper.
designated as follows:
The recognized types investigated may be
(I) Festuca scabrella Type, including
study sites I and 2; (2) Festuca idahoensis Type, including
study sites 3-7; (3) Agropyron spieatum Type, including study
sites 8-12; (4) KbeTeria-Stipa-Agropyron Type, including study
sites 13-22; (5) Stipa-Agropyron-Bouteloua Type, including
study sites 23-35; (6) Bouteloua-Carex-Stipa Type, including
study sites 36-46; (7) Bouteloua-Stipa Type, including study
47-58; (8) Buchloe-Bouteloua-Agropyron Type, including study
sites 59-62; (9) Bouteloua-Agropyron Type, including study
sites 63-70; (10) Agropyron smithii Type, including study
sites 71-75; ( H and 12) Artemisia tridentata and Sarcobatus
vermiculatus Types, including study sites 76-79; and (13)
Abandoned Fields, including study sites 80-105.
Within each site selected for study a detailed investi­
gation was made of the vegetation and the grasshoppers pres­
ent.
A "point-plot" method of studying vegetation was
employed at each study site.
A set of 10 steel surveyor's
arrows, 14 % 3/l6 in, were held in place 4 in apart along a
wooden board.
This apparatus was placed 50 times at random
within each site.■ Each "hit" of a plant taxon at ground level
-
I
-
by an arrow-point was recorded and contributed to the measure
of basal cover and percentage composition by each taxon.
At a
few sites the estimate of percentage composition was based
upon the establishment of 4-sq-ft list quadrats in which indi­
viduals of each plant species were counted and recorded.
When
an arrow struck litter it was recorded and contributed to the
measure of the amount of ground covered by litter.
Total
foliage cover was measured by recording any touch by plant
foliage on an arrow above its point.
A summary of the vege­
tation measurements for all study sites is presented in Table
I.
Field records of species occurrence, taken over a period
of 12 years, were used in establishing the general grasshopper
species distribution.
At some of the study sites it was pos­
sible to obtain quantitative data on grasshopper populations
present by use of bottomless cages placed at night.
This
"night cage" method of sampling has been described previously
by Anderson & Wright (1952) and Anderson (1961).
At most
study sites, however, grasshopper population density was
merely estimated and recorded along with a list of species
observed.
Approximate order of species abundance was deter­
mined from sweep-net collections.
The identification of all
grasshopper species was based primarily upon the reference
collection at Montana State College.
TABLE I.
A summary of study site vegetation measurements.
% Composition
% Basal Cover
Study Site
I.
2.
3.
4«
5.
6.
7.
8.
9.
10.
11.
12.
13.
14«
15.
16.
17.
18.
19.
20.
21.
22.
23.
24.
2$.
26.
27.
28.
Grasses
"" & '
Sedges
Forbs
& ’'
Shrubs
41
30
33
34
Total
16
20
16
71
59
48
41
52
33
31
33
36
21
19
32
6
26
15
20
29
5
4
11 •
4
6
5
19
14
4
5
2
5
6
I
35
34
19
26
14
15
8
14
21
26
44
19
10
11
19
5
5
22
17
16
14
15
25
24
25
20
14
16
36
18
18
17
17
24
•
'
36
28
31
25
33
30
40
23
20
22
23
25
Grasses
& '
Sedges
58
44
29
36
15
42
67
67
48
76
73
50
76
43
85
81
70
86
79
79
42
52
90
79
92
76
75
97
Forbs
:
:
% Foliage
Cover
% Litter
Shrubs :
42
56
71
64
85
58
33
33
52
24
27
50
24
57
15
19
30
14
21
21
58
48
10
21
8
24
25
3
77
. 47
79
37
36
72
8
21
42
24
11
16
65
21.
20
16
27
15
11
4
44
48
56
20
33
30
53
17
100
66
69
65
31
66
32
28
.
39
21
8
19
49,
37
27
15
47
35
3 .
21
22
25
65
8
2
26
50
15
TABLE I. (Continued)
29,
30,
31.
11
40
32.
33:
34.
35.
75
65
15
36.
37.
38.
39.
40.
41.
42.
43.
44.
45. .
46.
47.
48.
49.
50.
51. .
52.
53.
5k.
73
17
8
5
2
I
6
3
6
I
3
8
3
7
7
6
8
I
2
I
4
3
7
8
3
2
11
10
7
39
20
71
3
7
5
I
3
3
48
58
38,
32
29
21
11
39
17
25
51
19
69
31
26
35
9
17
71
51
21
52
56.
57.
58.
5960.
6l.
62.
63.
36
41
23
38
33
28
48
53
77
66
21
61
44
33
32
39
83
90
97
97
94
95
87
97
91
29
72
' 14
46
24
31
59
77
85
72
20
95
71
98
96
87
32
30
38
.16
25
74
53
32
62
80
59
74
. 43
46
'24
41
36
81
87
93
56
67
96
98
66
84
91
66
95
85
89
95
93
92
61
17
10
3
3
6
5
13
3
9
28
23
15
28
19
13
5.
2
4
13
7
44
33
4
2
34
16
9.
■ 34
5 .
15'
11
5
7
8
53
6
8
28
60
81
9%
65
39
54
43
17
66
67
2
20
22
14
15
12
8
2
3 .
I
2
10
50
46
6
48
23
2
20
33
I
5
3
I
I
2
32
62
3
3
7
8
2
2
3
I
2
2
I
2
I
13
I
6
I
2
24
23
12
15
I
41
4
18
6
2
1
vO
I
TABLE I, (Continued)
22
64»
65.
66.
13
61
67.
68:
69.
70.
71.
72.
73.
74.
75.
76.
77.
78.
79.
80.
81.
82.
83.
84.
85.
86*
%
'
88.
89.
90.
91.
92.
93.
'
64
72
34
19
11
12
9
12
30
9
13
3
4
42
19
25
6
14
18
13
14
17
21
23
29
12
56
94«
15
95.
96.
97.
98.
23
69
92
64
I
23
96
5
9
18
70
73
I
65
82
10
■ 19
.24
2
3
11
11
3
32
22
20
23
2
36
53
43
13
15
20
23
33
41
34
23
27
44
55
21
19
13
25
9
I
46
I
I
18
22
19
27
24
3
27
I
42
I
6
I
25
27
43
22
15
56
36
59
42
24
70
98
65
87
99
88
64
44
4
27
13
I
12
36
56
86
14
78
44
53
91 '
22
20
37
14
14
95
40
54
25
52
41
60
99
95
99
55
52
33
95
36
99
99
95
98
56
47
9
80
63
86
86
5
60
46
75
48
59
40
I
5
I
45
48
67
5
64
I
I
5
2
2
8
33
9
23
55
48
35
62
51
2
2
I
I
I
80
19
17
22
33
37
45
31
43
5
7
40
26
35
9
5
64
89
8
41
31
2
23
28
15
20
65
76
32
54
35
58
38
76
75
85
65
2
41
91
23
17
50
16
5
50
2
2
2
20
78
79
50
TABLE I. (Concluded)
99.
100.
101.
102.
103.
104;
105.
29
31
22
13
6
9
2
22
27
6
27
31
3
25
'
51
58
28
40
37
12
27
57
54
79
16
75
7
43.
46
21
67
84
25
93
33
51
85
54
51
58
35
28
60
79
55
39
5
2
I
H
H
I
12
GRASSHOPPER SPECIES DISTRIBUTION
The following grasshopper species were encountered during
the course of the study.
Unless otherwise indicated, each
species was recorded in field notes during the past 12 years
from all counties east of the Rocky Mountains.
Acrolophitus hirtipes (Say)
Field notes record the presence of this species in every
county except Beaverhead.
It was found on study sites 3, 5 »
19, 29, 31, 34, 39, 50, 59, 72, 73, 74, and 96.
A. hirtipes
was never found in high numbers and seemed to be restricted
to areas of sparse vegetation.
In accordance with previously
recorded food-plant preferences (Griddle 1933, Anderson &
Wright 1952) it was always associated with the presence of
members of the plant family Boraginaceae.
Aeoloplus turnbulli turnbulli (Thomas)
This species was recorded as being present on study sites
63, 65, 72, 73, 76, and 77«
numerous.
At no time was it considered
The usual situation was to find from one to several
pairs congregated in a relatively small area and invariably
associated with members of the plant family Chenopodiaceae
(Griddle 1933, White & Rock 1945, Anderson & Wright 19.52).
Because of the low numbers usually present and the localized
distribution of this species it is possible that A. turnbulli
was present on more of the study sites than recorded.
It is
rather surprising that it was not recorded from a number of
the abandoned fields in which members of the Ghenopodiaceae
were commonly encountered.
Aerochoreutes carlinianus carlinianus ■(Thomas )
A* carlinianus was recorded from study sites 10, 29, 39,
72, 73, and 74.
Although Griddle (1.933) and Brooks (1953)
record this species as one which feeds mainly on Agropyron
smithii there was no indication of any association with a
particular plant or group of plants.
On the contrary, the
adults were most commonly found during the heat of the day
hovering over bare ground and rocky outcroppings.
Aeropedellus clavatus (Thomas)
A.
clavatus was one of the most commonly found species,
occurring in numbers greater than I per sq yd in both native
grassland areas and abandoned fields.
It was listed from
study sites 2-6, 8, 9, 13-20, 23-29, 31, 39, 41, 42, 47-49,
51, 59-61, 71-74, 76, 79, 82, 85, and 86.
It may not have
been encountered on some sites since it is an early-hatching
species which has normally oviposited and disappeared by midJuly.
Although there appears to be some association between
this species and Koeleria cristata it is believed that the
association is one involving the availability of green, succu­
lent grass which is satisfied by K. cristata early in the
season.
A. clavatus is known to feed on several grass species
(Anderson & Wright 1952).
— li). —
Ageneotettix deorum (Scudder)
A. deorum was listed on study sites 4»
12-21, 28-31#
33, 34, 37, 39, 40, 43, 44, 46, 47, 49, 50, 53, 54, 56-67,
70-75, 80-85, 87-89, 93, 95-101, and 104.
It occurred in
numbers greater than I per sq yd on both native grassland and
abandoned fields.
It appeared to inhabit a variety of habi­
tats but is most common and often abundant in areas of short
grass and bare ground.
Dry conditions are particularly
favorable to this species (Allred 1941)«
From the standpoint
of food-plant preference A. deorum can be considered a grassfeeding species with little or no specific plant preference
(Griddle 1933; Anderson & Wright 1952).
It includes consider­
able dry material in its diet as an adult and can be in fairly
high numbers without inflicting measurable damage to green
vegetation (Anderson 1961).
Amphitornus coloradus (Thomas)
This species was recorded from study sites 4, 8, 9, 11,
12, 14, 15, 17-20, 28-33, 36, 37, 39, 44, 50, 55-57, 59,
64-66, 68, 70-74, 76, 80-82, 87, 88, 9#, and 100.
At times
it was found in numbers greater than I per sq yd on both
native grassland and abandoned field study sites.
This grass-
feeding species (Griddle 1933, Ball et al. 1942, Anderson &
Wright 1952, Brooks 1958) was most common in areas where there
was a mixture of Bouteloua gracilis and Stipa comata.
It not
only feeds on these two grass species but also climbs upon and
- 15 -
'remains inactive on the taller S . comata for long periods'.
Arphia conspersa Scudder
A. conspersa was listed on study sites 29, 32, 37-39, 55,
56, 60, 61, 66, 63, 70, 72-74, 79, 91, and 102.
It over­
winters in one of the later nymphal instars and appears as an
adult early in the spring. -Consequently, it may have ovi­
posited and disappeared before many of the study sites were
established.
This grass-feeding species was not found associ­
ated with any specific food-plants and has not been noted in
abundance.
It appeared to be most common in dry upland situ­
ations on sandy soil and often in association with open stands
of Pinus ponderosa.
Arphia pseudonietana pseudonietana (Thomas)
A. £0 pseudonietana was listed in low numbers from study
sites 7, 12, 17, 29, 33, 34, 36, 39, 41, 46-43, 52-55, 57, 66,
63, 72-74, 33, 39, 94, and 95.
Although this spring-hatching
species is one of the grass-feeders (Anderson & Wright 1952),
it was not found associated with a specific food-plant or
group of food-plants.
A. p. pseudonietana and A. conspersa
appeared to occupy similar habitats in Montana with A. p.
pseudonietana being more commonly encountered at lower eleva­
tions and most numerous in areas of mixed short- and mid-grass
vegetation.
Aulocara elliotti (Thomas)
This species was listed from study sites 9, 11, 14-13,
- 16 -
22, 29, 30, 37, 39, 40, 44, 50, 54, 56, 57, 64-66, 71-75, 83,
84, 87, 89, 91, 93-95, 100, 102, and 104,
A. elliotti may be
considered the most abundant and injurious of the species
found oh Montana grasslands year after year.
During the study
period it appeared in numbers greater than I per sq yd on both
.native grassland and abandoned field sites.
It is a grass-
feeding species (Griddle 1933, Ball et al. 1942, Pfadt 1949,
Anderson & Wright 1952, Brooks 1958) which shows definite
preference for Agropyron spp.
It is often found to be very
abundant in stands of Agropyron smithii or in fields planted
to Agropyron cristatum.
It may also be numerous in areas,
where A. smithii is but a minor part of the total vegetation
complex.
The local distribution of A. elliotti on native
grasslands or medium-aged abandoned fields is usually gov­
erned by the distribution of A. smithii, with the greatest
concentrations found where the density of A. smithii is
highest.
Boopedon nubiIurn (Say)
B.
Montana.
nubilum has been encountered on few occasions in
During the past 12 years it has been found in all
counties north of the Missouri River and east of the eastern
edges of Toole, Pondera and Teton counties.
It has also been
found in counties south of the Missouri River which lie east
of Wheatland county.
15 and 71.
It was listed from only 2 study sites,
According to Ball et al. (1942) it is one of the
- 17 -
most ’’common and conspicuous of Arizona grassland species”
and was found to be "more common in areas of Andropogon,
Aristida, and other tall grasses„ than in areas of curly
mesquite (Hilaria) and Bouteloua’’«
Limited observations in
Montana indicate that it is a grass-feeding species which is
associated with dense stands of Agropyron smithii growing in
moist depressions or swales.
At no time was B„ nubiIum
abundant or found commonly over a very large area.
Brachystola magna (Girard)
This species was rarely encountered during the study.
It
was not listed for any of the study sites but was recorded in
field notes from Yellowstone, Big Horn, Rosebud, Ouster,
Prairie, Dawson, and Richland counties.
The few B. magna.
observed were found along highway borrow-pits or in areas of
sparse grass and forbs such as Helianthus annuus, Sphaeralcea
eoccinea, and Monolepis nuttalliana.
Bradynotes obesa (Thomas)
This rare species was recorded in field records from only
3 areas.
These were southeast of Red Lodge, Carbon county,
south of Livingston, Park county, and west of Dell, Beaverhead
county.
It was listed on study site 11.
In every instance it
was found where the vegetation was sparse and of low stature
on an outwash fan at the base of a mountain range.
No field
observations were made which would associate this species with
any plant or group of plants.
Bruneria brunnea (Thomas)
B. brunnea was recorded from all counties as far east
as Blaine county on the north and western Big Horn county on
the south.
It was also found in the northeast corner of the
state in Daniels, Sheridan, and Roosevelt counties =
It was .
listed from study sites 2, 8, 1$, 20, k 5 , 47» 58, 69, 82, 88,
and 98.
It occurred in numbers greater than I per sq yd in a
few grassland sites but not on abandoned fields.
This grass-
feeding species (Griddle 1933, Brooks 1958) was found to be
most abundant on upland areas characterized by the presence of
Koeleria cristata, Stipa comata, and Agropyron smithii with an
understory of Carex filifolia, Bouteloua gracilis, and
Selaginella densa.
Bruneria sordida (McNeill)
This species was noted on only two occasions when it was
listed for study sites 10 and 11 in Beaverhead county.
specimens were seen at these locations.
Few
In both instances
the vegetation was sparse and of low stature on an outwash fan
at the base of a mountain range.
Camnula pellucida (Scudder)
C . pellucida was recorded from study sites 2, 4, 7 ,
80-82, and 86, occurring in numbers greater than I per sq yd
on some abandoned field sites but in lower numbers on all
native grassland sites.
This species is listed by Griddle
(1933) as a grass-feeding species which also feeds on "a few
- 19 -
broad-leaved plants"*
He and other Canadian workers have con­
sidered Ce pellucida to be one of the most serious pests in
cropland areas of the prairie Provinces.
On Montana grazing
lands and abandoned fields its local distribution is usually
predictable due to a close association with Poa spp., in
particular Poa pratensis.
It has also been noted on occasion
in fields planted to Agropyron cristatum but has not been
found generally common in fields of small grain.
Exceptions
to this have been noted in the extreme northeastern Montana
counties of Sheridan, Daniels, and northern Roosevelt where
C . pellucida has often been found in grain fields and also has
earned the common name "roadside grasshopper" by which it is
often referred to in Canada.
Ghorthippus longicornis (Latreille).
This species has been found on few occasions from
Glacier, Toole, Liberty, and Hill counties on the north, and
Beaverhead, Madison, Broadwater, Gallatin, Park, Meagher,
Sweetgrass, Stillwater, Carbon, and Yellowstone counties on
the south.
It was listed from study site I.
C . longicornis
is listed.among the grass-feeding species by Griddle (1933)
and Brooks (1958).
It was found at elevations between $,000
and 7,000 ft in Montana and usually in areas where seeping
water or flowing springs had created wet conditions.
20
Chortophaga viridifasciata (Be Geer)
C e viridifasciata was recorded for Beaverhead, Madison,
Gallatin, Broadwater,: Park, Meagher, and Big Horn counties =
It was listed from study sites 7, 29, 39, and 72-74.
This
grass-feeding species (Griddle 1933, Brooks 1953) appears as
adult early in the spring, oviposits, and disappears by midJuly which may account for it not being listed more often.
It
appeared to occupy habitats similar .to those of Arphia cpnspersa and generally could be found also early in the spring
in lush vegetation along the banks of slow moving streams.
Here the green color phase appeared to be more common than
the brown.
It was never found in abundance.
Circotettix rabula rabula Rehn and Hebard
This species was recorded in field notes from all coun­
ties south of the Missouri River except Cascade, Chouteau,
Judith Basin, Fergus, and Petroleum.
North of the Missouri
River it was recorded from all counties east of Hill county.
It was listed from study sites 10, 12, 17, 29, 39, 50, 72-74,
76, 79, and 103«
C_« r. rabula is listed among the mixed-
feeding species by Griddle (1933) and Brooks (1953).
In
Montana, the adults appear to prefer bare spots and eroded
areas and often are seen hovering over these areas on warm
days as has been mentioned for Aerochoreutes carlinianus.
Both of these species are difficult to catch in a sweep-net
and were often listed on the basis of sight and sound records.
21
C . r . rabula was never found in abundance«
Cordillacris crenulata (Bruner)
Field notes record this species south of the Missouri
River from all counties except Jefferson, Meagher, Broadwater,
Judith Basin, and Fergus„
North of" the Missouri River it was
recorded from all counties east of Toole county.
It was
listed from study sites 8, 10-12, 23, 28, 46, 53? 57? 62, 64?
and 6?.
C.. crenulata is a grass-feeding species which occurs
most commonly, at times abundantly, in the short-grass plains
areas.
It is especially common on Bouteloua gracilis, Buchloe
dactyloldes, and Carex'filifolia.
Cratypedes negleetus (Thomas)
This species was found in low numbers on.foot-hills areas
east of the Rockies in all counties as far as Blaine county on
the north and Yellowstone county on.the south.
listed from study sites 8, 12, 17, and 50.
It was also
This species is
listed by Griddle (1933) among those which feed on several
species of broad-leaved plants.
Brooks (1958) says "the spe­
cies is primarily a grass-feeder".
It was found to be most
common in areas of dense, tall vegetation comprised of a mix­
ture of grasses and of forbs such as Oxytropis spp.,
Astragalus spp., and Lupinus spp.
Dactylotum pictum (Thomas)
This species was not listed from any of the study sites.
Only a few individuals were recorded in field notes from
-
22
low-stature vegetation in southeastern Big Horn, Rosebud,
Powder River, Ouster, Dawson, Richland, and Roosevelt coun­
ties.
Those few specimens noted were on rocky areas of sparse
vegetation.
Derotmema haydenii haydenii (Thomas)
h. haydenii was listed from study sites 2 9 , 3 9 , 72-74,
D.
83, 94, and 99•
This species is very localized in its distri­
bution but was found to be numerous.in some small areas.
It
appeared to be a forb-feeding species (Anderson- & Wright 1952)
which preferred areas of dry, sparse vegetation.
It was most
commonly encountered in areas of highly compacted soil such as
may be found in a dry stream bed, the mounds of an old prairie
dog town, or a heavily grazed area on heavy clay soil.
Dissosteira Carolina (Linnaeus)
This species was recorded from study sites 50, 72-74, 77,
and 94*
It is listed among the mixed-feeding species by
Griddle (1933) which "prefers broad-leaved plants". As an
adult it frequently congregates on dusty, barren areas such
as a dirt road or fallowed field and may thus occur in high
numbers within a small area.
D. Carolina appeared to spend
little time feeding as an adult.
It has strong flying capa­
bilities which prevent it from being captured readily by
sweeping and it may have been overlooked on a number of the
study sites;
- 23 Drepanopterna femoratum (Scudder)
Field notes show D. femoratum present in all counties
except Madison and Jefferson.
It was also listed from study
sites 1$, 28, 29, 33, 34, 37, 47, 54, 57, 63-65, 71-75, 93,
94, 96, 97, 101, and 104.
It occurred in numbers greater than
I per sq yd on some native grassland sites but not on aban­
doned fields.
This grass-feeding species shows a preference
for Agropyron smithii (Anderson Sc Wright 1952).
Although the
distribution of this species appeared to be partly correlated
with the presence or absence of A. smithii, it was definitely
not as wide-spread in distribution as is A. smithii.
As a
later instar nymph and adult it congregated and was most
numerous in the dry plains areas of heavy clay soil.
'Eneoptolophus sordidus costalis (Scudder)
This species was listed from study sites 31, 36, 63, 66,
72-74, 94, 96, and 100.
grassland habitats.
It was found in low numbers in dry
It has been listed among the grass-
feeding species (Griddle 1933, Anderson & Wright 1952, Brooks
1958) and seemed to be most common on poorly drained clay
soils dominated by Agropyron smithii.
Eritettix simplex tricarinatus (Thomas)
This species was listed from study sites 12, 13, 16, 27,
29, 32, 33, 35, 39# 54, 56, 6l, 66, and 72-74.
First instar
nymphs were generally found between 15 August and I September
and in numbers great enough to make this species dominant at
TT
— 24 —
that time.
The adults which appear early in the spring appar­
ently disappear early in the season since only an occasional
individual adult was noted after mid-July.
Limited feeding
observations indicated that-E. s_. tricarinatus is a grassfeeding species.
It was found to be most abundant in short-
grass areas dominated by Bouteloua gracilis and was noted
feeding on this grass.
Hadrotettix trifasciatus (Say)
H. trifasciatus was recorded from study sites 15, 29, 39,
50, 57, 67, 70-74, 76, 77, #2, #7, 89, and 95.
was common but never found in high numbers.
This species
It is listed
among those species which feed on broad-leaved plants by vari­
ous workers (Griddle 1933, Isely 1938, Ball et al. 1942) and
has been observed to include considerable amounts of dry plant
material in its diet (Anderson & Wright 1952).
H. trifascia­
tus was most commonly found in areas of sparse, dry, lowstature vegetation but did not appear to be associated with
a specific plant or group of plants.
Hesperotettix viridis pratensis (Scudder)
H. y. pratensis was listed from study sites 5, 8, 12, 14,
17, 21, 29, 39, 40, 50, 57, 70, 72-74, 81^84, 89, 94, 95, and
100.
It occurred in numbers greater than I per sq yd on some
native grassland sites but not on abandoned field sites.
Although this species was frequently encountered, its local
distribution was closely associated with particular '
- 25 food-plants.
It was most abundant in association with
Gutierrezia sarothrae.
Other plants with which it was occa­
sionally found associated were Solidago spp., Haplopappus
spp., and Chrysothamnus spp.
Hippiscus rugosus (Scudder)
Field records show H. rugosus present in Big Horn,
Rosebud, Custer, and Powder River counties.
from study sites 29, 39, and 74.
It was recorded
This species has been noted
in very low numbers on gravelly slopes which support tall
grasses such as Agropyron spicatum,.Andropogon scoparius. and
Boutelo.ua curtipendula.
It was previously observed that,
while these grasses appear to-be preferred by the adults, the
early instar nymphs confine their feeding to the low-growing
Bouteloua gracilis (Anderson & Wright 1952).
Hypochlora alba (Dodge)
H. alba was listed for all counties north of the Missouri
River and east of the Rocky Mountains.
South of the Missouri
River it was listed for all counties east of Meagher.
It also
appeared on records for study sites 15, 28, 29, 33, 39, 65,
and 72-74.
This species was found to be extremely local in
distribution and invariably associated with Artemisia Iudoviciana.
Melanoplus alpinus (Scudder)
A few field notes record this species from Beaverhead,
Madison, Gallatin, Park, Sweetgrass, Carbon, and Glacier
rt_ M T
- 26 counties.
The only study site for which it was listed is 2.
The few specimens observed have been in short vegetation with
interspersed open areas at elevations exceeding 6,000 ft.
Brooks (195&) says this species feeds on grass in Canada..
Melanoplus bilituratus (Walker) l/
M.. bilituratus was listed from study sites 3-5, 7-9, 11,
13-17, 21, 22, 28-30, 32, 33, 37, 39, 40, 50, 54, 56, 57, 64,
65, 70-76, 80-87, 91-97, and 101-105.
It occurred in numbers
greater than I per sq yd on some study sites in both native
grassland and abandoned fields.
This is probably the most
common species found on Montana grasslands and occurs in a
greater variety of habitats than any other species.
It is
considered to be a mixed-feeding species which shows a pref­
erence for forbs as an adult (Anderson & Wright 1952).
This
preference for broad-leaved plants is reflected in the local
distribution of M. bilituratus.
During the study it was found
to be most abundant in areas of degenerated grassland where
the perennial grasses were depleted and annual grasses and
annual and perennial forbs were abundant.
It was particularly"
abundant on abandoned fields in the earlier annual grass and
l/
This species, formerly known as Melanoplus atlanis. M.
mexicanus mexicanus. and, since 1958, as M. bilituratus
is now named Melanoplus sanguinipes sanguinipes (F.) in
a recent paper by Gurney (1962).
- 27
forb or perennial forb stages of succession.
Melanoplus bivittatus (Say)
M. bivittatus was listed from study sites 3 , 7 , 10, 33,
39, 69, 71-74, 80-82, 92, 94, 103, and 105.
It occurred in
numbers greater than I per sq yd on some abandoned field sites
but in lower numbers on native grassland.
This species is a
mixed-feeder which shows a preference for forbs. While it
was most common and abundant in cropland areas, it was also
found associated with forbs, on grasslands.
It was not numer­
ous on these grassland areas but was often abundant and one of
the dominant species present on abandoned fields in the early
stages of plant succession.
Melanoplus bowdltchi canus (Hebard)
This species was recorded from all counties east of Toole
county on the north and Madison county on the south.
It was
listed from study sites 22, 29, 39, 72-74, 76, 88, 98, and
100.
M. b. canus shows a very strong feeding preference for
Artemisia cana (Griddle 1933, White & Rock 1945, Anderson &
Wright 1952, Brooks 1958), and its occurrence was correlated
with the distribution of A. cana within an area.
Melanoplus bruneri (Scudder)
This species was recorded from mountain meadows above
6,000 ft as far east as Carbon county.
being present on any of the study sites.
It was not listed as
It was noted to be
abundant at 2 locationsj one on the west side of the Crazy
Mountains and the other on the east slopes of the Crazy
Mountains.
Both areas were similar to those described by
.Kreasky (I960).
Kreasky observed that this species thrived
"in weedy habitats in which Lupinus sericeus (lupine) is usu­
ally one of the dominant plants” .
He noted further that it
fed primarily on L. sericeus but turned to Phleum pratense
when L. sericeus was depleted.
Brooks (1953) says "the
species is a mixed feeder, preferring grasses".
Griddle
(1933) says "its food habits are quite diversified" and states
further:
"This insect is an inhabitant of shrubby areas in
which there are open spaces.
We have found it most frequently
in openings among mixed'woods in which its chief plant asso­
ciates were Amelanchier, Symphoricarpos, Arctostaphylos and a
few coarse grasses or herbaceous plants".
Melanoplus confusus (Scudder)
This species was recorded in field notes from all coun­
ties except Glacier and Beaverhead.
It was listed from study
sites 3-6, 8, 9, 12-15, 17, 20, 26, 27, 29, 31, 33, 37, 39,
41, 50, 6l, 71-74, 8l, 82, 85, 88, and 98«
It was present in
numbers greater than I per sq yd on some native grassland
,sites but in lower numbers on abandoned fields. M. confusus
hatches early in the spring and appears as an adult before any
others of this genus.
It occurred commonly in some areas
until mid-July and only an occasional straggler remained by
mid-August.
Both Griddle (1933) and Brooks (1958) consider it
— 29
to be a mixed-feeder in Canada.
—
Griddle, however, states that
it "prefers grass", while Brooks states that it "prefers
forbs".
Feeding observations in Montana indicate that it pre­
fers forbs and, although it is widespread in its distribution,
it was found to be most abundant in dry, sandy areas occupied
by forbs and low-stature shrubs.
Melanoplus dawsoni (Scudder)
..
This species was listed from study sites 2-5, 13, 17, 23,
24, 29, 39, 41, 70-74, Si, 82, .84," and 85-
It occurred in
numbers greater than I per sq yd on some native grassland
sites but in lower numbers on abandoned fields.
M= dawsoni
is one of the latest species of the genus to hatch in the
spring.
It was commonly encountered and, at times, abundant
in open sandy areas with a cover of low-growing forbs and
shrubs such as Symphoricarpos spp., Rosa spp., Solidago spp.,
Aster spp., and Lupinus spp.
It feeds mainly on these broad­
leaved plants in Montana (Anderson & Wright 1952).
Melanoplus differentialis (Thomas)
This species was noted in counties east of Stillwater
county, south of the Missouri River, and counties east of
Valley county on the north.
only.
It was listed from study site 74
Although this species occurs most commonly in cropland
areas, occasional individuals are found on grassland.
The
only feeding observation of M- differentialis on grassland was
at study site 74 where it fed on Psoralea tenuiflora.
- 30 -
Melanoplus femur-rubrum femur-rubrum (Be Geer)
This species was listed from study site 74 only.
It has
been found to be most abundant in irrigated cropland areas and
was found only in low numbers on grassland areas *
This mixed-
feeding species appeared to be confined in its grassland dis­
tribution to moist areas such as occur around livestock
drinking sites and about the banks of slow moving streams.
Melanoplus gladstoni (Scudder)
This species was listed from study sites 9, 1$, 30, 44,
54, 55, 68, 72-74, 84, 89, 92, 94, 95, 100, and 10$.
In
Canada, Griddle (1933) considered M= gladstoni to be a grassfeeder while Brooks (1958) states that it is a "general mixed
feeder".
The few observations on its feeding in Montana indi­
cated that it feeds on both forbs and grasses.
It was never
found abundantly but. was most commonly encountered in dry
areas of grasses such as Bouteloua gracilis, Agropyron
smithii, Stipa cpmata, and Koeleria cristata along with a
mixture of low-stature forbs.
Melanoplus infantilis (Scudder)
This species was listed from study sites 8, 10, 12,
17-25, 27, 28 , 30, 31, 33-36, 41-43, 45-55, 58, 59, 63-66, x
68-70, 72-74, 83, 84, 86, 88, 90, 91, and 97-103.
It occurred
in numbers greater than I per sq yd on some native grassland
and abandoned field sites.
Griddle (1933), Isely (1944), and
Anderson & Wright (1952) considered M= infantilis to be a
- 31 grass-feeding species.
Brooks (1958) states that it is a
"mixed feeder, preferring grasses".
This species was found to
be widespread and, in some areas, numerous on Montana grass­
lands.
It was nearly .always among the species inhabiting
short-grass sites dominated by Bouteloua gracilis and the
sedge Carex filifolia.
It was also found in areas dominated
by taller grasses such as Agropyron smithii, Stipa cpmata, and
Koeleria cristata but generally in lower numbers than on the
short-grass areas.
Melanoplus keeleri luridus (Dodge)
M. k„ luridus was recorded in field notes from counties
north and east of Yellowstone county.
sites 17, -18, and 74°
It was listed for study
The few individuals of this species
which have been noted appeared to be confined to ravines and
gravelly hillsides where a variety of forbs and low shrubs
were present.
Griddle (1933) lists it among the mixed-feeding
species => The few feeding observations on this species in
Montana have found it to be restricted to several forbs.
Melanoplus kennicotti (Scudder)
Only 3 records were.made of the presence of this species,
all at elevations above 5,000 ft.
It was seen south of
Livingston, Park county, north of Red Lodge, Carbon county,
and on study site 2 in Glacier county.
tions were made in Montana.
No feeding observa­
In Canada, however. Griddle
(1933) has listed it among the grass-feeding species while
- 32 Brooks (195$) states that "it definitely prefers forbs but
will eat grasses and sedges".
Melanoplus montanus (Thomas)
A few specimens of this species were recorded above 6,000
ft in Gallatin, Park, and Glacier counties.
from study site I.
It was listed
The few individuals observed have been in
areas of dense vegetation but with an apparent preference for
open spots within the habitat.
No observations on feeding
habits of this species were made.
Griddle (1933) lists it
among the species which feed on broad-leaved plants.
Melanoplus occidentalis occidentalis (Thomas)
This species was listed from study sites 5, 6, 9, 11-14,
16, 31, 34, 37, 43, 50, 57, 65, 71-74, $3, and $7.
It
occurred in numbers greater than I per sq yd on some native
grassland and abandoned field sites.
M. 0 . occidentalis was
found to be most common and at times abundant in the dry
grassland areas of the state.
It was often one of the domi­
nant species along with Aulocara elliotti in areas of
Agropyron s m i t h i i a food-plant which it prefers (Griddle
1933)<>
It is not, however, a strict .grass-feeder but has been
observed to include various forbs in its diet.
It appeared to
be restricted somewhat in its distribution by an apparent
preference for areas of sandy loam soil.
Melanoplus oregonensis (Thomas)
■A few field notes record the presence of this species
- 33
above 5,000 ft in Gallatin, Park, and Sweetgrass counties.
It was not listed from any of the study sites„
instances, it was found in very low numbers.
In most
However, on one
flat, gravelly area near the northeast end of the Crazy
Mountains it was the dominant species.
The vegetation of the
area was a mixture of Festuca idahoensis and many forbs such
as Lupinus sp., Arnica sp., Senecio sp., Taraxacum sp.,
Geranium sp., and Gaillardea sp.
The few observations on
feeding by this species indicated a definite preference for
broad-leaved plants.
Melanoplus packardii (Scudder)
M. packardii was listed from study sites 4# 7, 8, 11, 12,
1—I
, 20-22,, 2914, 17:, IS3
39, 40, 43, 44, 50, 54, 57, 60, 69,
70, 72--74, 80-85, 87, 89, 92, 94, 95, 100:, 103,- and 105.
Some
sites on both native grassland and abandoned fields harbored
numbers of this species greater than I per sq yd.
It was
found to be most abundant in areas of sandy or gravelly soil
and particularly on abandoned fields in early stages of plant
succession.
It is considered to be a general-feeder (Anderson
& Wright 1952) but in grassland areas showed a definite pref­
erence for members of the Leguminosae.
The blossoms of vari­
ous forbs especially are selected for feeding by this
grasshopper.
Mermiria maculipennis macclungi (Rehn)
This species was recorded in field records- from all
- 34 -
counties north and east of Yellowstone county.
from study sites 74 and 76.
It was listed
It was never found in high num­
bers and was restricted in its distribution to sandy and rocky
hillsides where tall grasses such as Bouteloua curtipendula
and Galamovilfa IongifoIia were common. ■ Late in the season it
commonly occurred in deep coulees in association with tall
grasses present there.
Metator pardalinus (Saussure)
M. pardalinus.was listed from study sites 9, 12,.14, 15,
17, 28, 29, 31, 37, 47, 50, 51, 54-56, 64-66, 68,, 71-75,.82,
83, 86, 88-90, 93-95, 98, 100, 103, and 104.
It occurred in
numbers greater than I per sq yd on some native grassland
sites but in lower numbers on abandoned fields.
This species
was found most commonly in the grasslands of the eastern part
of the state.
Although it will feed on a variety of grasses,
it showed a preference for Agropyron smithii.
When numerous,
it appeared to be gregarious and as a later instar nymph and
adult was found congregated in large groups.
Local movement
of the intact group was common (Anderson & Wright 1952).
Neopodismopsis abdominalis (Thomas)
This species was recorded in low numbers from Gallatin,
Park, Sweetgrass, Meagher, and Glacier counties.
listed for study site I.
It was
The few individuals observed have
been in dense vegetation of high mountain meadows.
According
to Brooks (1958) "the species feeds on several species of
grasses and sedges”„
Qpeia obscura (Thomas)
This species was recorded from all counties north of the
Missouri River«
South of the Missouri, it was found in all
counties east of Wheatland county.
It was listed from study
sites 15, 13, 23, 29, 31, 33, 36, 39, 47, 54-56, 63-65, 63,
72-74, and 96.
It occurred in numbers greater than I per sq
yd on some native grassland sites.
0. obscura was confined
in its distribution to areas of dry, short grass.
This grass-
feeding species has been observed to hatch after the mid-part
of June in Montana and to be most numerous in areas of
Bouteloua gracilis, Carex filifplia, and Buchloe dactyloides.
In areas where it could feed on any of a number of available
grasses it showed a definite preference for B 0 gracilis-.
This
is more in accord with the findings of Ball 'et al. (1942) and
Isely (1946) for Texas and Arizona than with the Canadian
reports of Griddle (1933) and Brooks (1953) who state that 0.
obscura prefers Agropyron .smithii.
Orphulella pelidna pelidna (Burmeister)
This species was not listed from any of the study sites.
A few field notes from Madison, Gallatin, Park, Stillwater,
Carbon, and Yellowstone counties record it to be present in
low numbers.
In every case it was associated with a wet situ­
ation such as an irrigated p a s t u r e a swampy site, or along a
stream bank.
Orphulella speciosa (Scudder)
O. speciosa was not listed from any of the study sites =
It was recorded in field notes from Yellowstone, Big Horn,
Rosebud, Wibaux, Dawson, Richland, Roosevelt, Sheridan,
Daniels, and Valley counties.
It was generally found in very
low numbers among tall grasses on dry, sandy or gravelly hill­
sides.
In one area, however, it was found in abundance; this
area was the south-facing slope of the narrow valley which
separates the Wolf and Rosebud Mountains east of Lodge Grass,
Big Horn county.
Here it was associated with both Andropogon
gerardi and Bouteloua curtipendula upon which it was feeding.
In other areas grasses upon which it was observed feeding
included Andropogon scoparius, Agropyron spicatum, Agropyron
smithii, and Stipa comata.
0. speciosa is included among the
grass-feeders by both Griddle (1933) and Brooks (195$)«
Rhlibostroma quadrimaculatum (Thomas)
P. quadrimaculatum was listed from study sites $, 10, 12,
17, 1$, 20, 21, 27-31, 34-62, 64, 66-70, $4, $7, 3$, 90, and
9$.
It occurred in numbers greater than I per sq yd on some
native grassland sites but in lower numbers on abandoned
fields.
P. quadrimaculatum is most common on the dry grass­
lands of eastern Montana.
Invariably it was found associated,
at times in abundance, with Bouteloua gracilis or, when pres­
ent, Buchloe dactyloides. or both.
This was consistently
- 37 -
found to be the case even in areas where B.'gracilis consti­
tuted but a low percentage of the total vegetation and
occurred only in small scattered mats.
It is considered to
be a grass-feeding species by Griddle (1933), Isely (1944),
and Brooks (195$)•
Phoetaliotes nebrascensis (Thomas)
P. nebrascensis'was listed from study sites 15, 23, 2$,
31, 33, 36, 41, 49, 54, 63, 65, 66, 74, 75, $2, 36, 96, 97,
and 101.
It occurred in numbers greater than I per sq yd on
some native grassland sites, but in lower numbers on abandoned
fields.
Isely (1944) lists this species among those with
mixed-feeder mandibles.
In Canada, it was listed by Griddle
(1933) as eating mostly grass and by Brooks (195$) as "a very
general grass-feeder".
Whelan (193$) found in Nebraska it was
"mostly on grass, one on weeds, and one on Solidago rigida".
In Montana it was found to be a grass-feeding species with a
definite preference for Agropyron smithii (Anderson & Wright
1952).
It was found to be very localized in its distribution
within an area.
Early in the season it was in dense stands of
A. smithii growing on flat areas.
As these stands dried there
was movement to adjacent coulees and waterways where the
grasses remained green and succulent and in which dense stands
could be found.
Its local distribution thus appeared to be
greatly influenced by the density and succulence of the grass
vegetation.
This has been substantiated by observations of
-
-
Shotwell (193S) who states that it was "usually found in low­
lands where the vegetation is lush" and by Gantrall (1943) who
found it only in "those areas of hydrophytic environment that
are covered with heavy growth of commingled Galamagrostis
canadense and Carex".
Pseudopomala brachyptera (Scudder)
This species appeared in collections from Chouteau, Sweet
Grass, Petroleum, Musselshell, Big-Horn, and Rosebud counties.
It was listed for study site 74.
P. brachyptera occurred in
very low numbers and was confined to lush, vigorous growths
of grasses along waterways and in coulees.
On several occa­
sions it was observed feeding on tall, succulent Agropyron
smithii„
Its restriction to moist habitats elsewhere has been
reported by Walker & Urquhart (1940) in Ontario and by
Cantrall (1943) in Michigan.
Psoloessa delicatula delicatula (Scudder)
This species was listed from study sites 11, 16, 20-22,
29, 35, 37-39, 43-46, 52-62, 66-68, 70, 72-74, 86, 88, 90, 91,
98, 99, 102, and 103°
P . .d„ delicatula overwinters as a nymph
and appears as an adult early in the spring.
Few adults
remain after the middle of July so that it could easily be
overlooked in collections after that date and until a new
hatch appears in the fall.
It is most common in short-grass
areas but does not appear to be limited in its distribution
by any single plant or group of plants.
According to Brooks
- 39 (1958) this "subspecies feeds on several species of grasses
and sedges such as Stipa spp., Garex spp., Agropyron spp., or
Festuca spp.
Phlox hoodii Richards is also readily eaten".
Schistocerca lineata (Scudder)
S . lineata was recorded in field notes from scattered
areas within all counties east of Fergus county and was listed
from study site 74.
It was encountered most frequently in
shaded, moist ravines or moist upland flats where there was a
dense stand of Glycyrrhiza lepidota and some low-stature
shrubs.
S . lineata was found by Griddle (1932, 1933) to be
definitely associated with G. lepidota in Canada and to have
fed upon species of the genera Astragalus, Lathyrus, and
Vicia.
Brooks (1958) also reports that in Canada it is a
"forbs-feeder, preferring licorice root (Glycyrrhiza sp.)".
On the other hand. Ball (1936) and Ball et al. (1942) found
it feeding on the crowns of Bouteloua curtipendula in Arizona
and indicated that it fed on low plants and used tall plants
as shelter.
At one location in Montana, S . lineata was found
most commonly either perched on Rosa sp. or eating G. lepi­
dota.
Adults were also observed feeding on Solidago rigida
and Symphoricarpos orbiculatus very sparingly but were never
seen feeding on any of the grasses (Anderson & Wright 1952).
Spharagemon collare (Scudder)
This species was listed from study sites 20, 29, 40, and
72-74.
Although S . collare was common in grassland areas, it
— Zj-O —
appeared in low n u m b e r s I t seemed to feed on both forbs and
grasses with some display of preference for grasses. No par­
ticular association with any plant or group of plants was
noted.
Spharagemon equale (Say)
This species appeared to be more abundant on Montana
grasslands than Spharagemon collare»
It was listed from study
sites 5, 10, 17, 20, 21, 29, 30, 32, 34, 39, 40„ 43, 46,
53-55, 65% 67, 63, 70, 72-74, 33, 39, 92, 97, 99, 101, 103,
and 105.
The nymphs and adults were common on dry grassland
areas but dad not appear to be associated with any particular
plant or group of plants.
Griddle (1933) placed it among
those species which feed on broad-leaved plants but with a
preference for the Gruciferae.
Brooks (1953) also points to
its preference for the Cruciferae but considers it to be a
"mixed feeder on range grass".
On the basis of mandibular
morphology, Isely (1944) placed S . equale among the forb­
feeding grasshoppers.
Treherne & Buckell (1924), however,
reported that it caused considerable damage to "bunch grass".
'
Iu Montana it has been observed feedipg on both grasses and
forbs with no indication of preference for either (Anderson &
Wright 1952)o
It was noted that the adults often congregated
in small groups on vegetation-free areas. When disturbed,
they flew away, but within a short time reassembled upon the
same areas.
- 41 Trachyrhachys kiowa kiowa (Thomas)
This species was listed from study sites 10, 15, 17#
23-30, 35, 40, 43, 44, 46, 49, 50, 53, 54, 56, 57, 6l, 63-65,
67, 72-74, 87, 89, 90, and 95.
It occurred in numbers greater
than I per sq yd only on some native grassland sites.
T. k.
kiowa was generally most common in areas of Bouteloua gra­
cilis, a preferred food-plant (Ball et al. 1942, Anderson &
Wright 1952).
An exception to this was noted on a clay-soil
flat dominated by a sparse stand of Agropyron smithii.
On
this area, located approximately 2 mi- east of study site 72,
it was the dominant species and was feeding on A. smithii as
readily as on the scattered patches of B. gracilis present.
In another area it was associated with Buchloe dactyloides as
well as B. gracilis.
Trimerotropis bruneri (McNeill)
Field notes record this species from all counties east of
the Rocky Mountains except Glacier county.
study sites 22, 43# 50, 72-74.
It was listed from
T. bruneri was found in very
low numbers on dry grassland areas with low cover.
There was
no indication of association with a particular plant or group
of- plants.
A few feeding observations indicated that it pre­
ferred forbs.
Trimerotropis campestris (McNeill)
T. campestris was listed from study sites 7, 8, 10, 12,
17, 22, 29, 39, 45, 47, 49, 50, 58, 65, 66, 69, 72-74, 89, 92,
- 42 -
95, and 105.
This was the most common species of the genus on
dry grassland areas and occurred in numbers greater than.I per
sq yd on some native grassland sites.
Both Griddle (1933) and
Brooks (195#) considered it to be a mixed-feeding species in
Canada.
The observations in Montana agree with this but there
was no indication that it showed a preference for grasses as
Brooks stated.
Trimerotropis cincta (Thomas)
A few individuals of this species were recorded in field
notes from Musselshell, Yellowstone, Big Horn, Rosebud, and
southeastern Garbon counties.
72-74.
It was listed from study sites
There were insufficient observations on this species
to come to any conclusions concerning feeding-habits or asso­
ciations with vegetation.
Those individuals encountered on
rare occasions were found in rocky locations occupied by a
very sparse stand of vegetation.
Xanthippus corallipes (Haldeman)
X. corallipes was listed from study sites 2, 6, 7, 9,
12, 14, 15, 18, 22, 24, 29, 31, 35, 37, 39, 41, 43, 45, 48,
52, 57-59, 66, 69, 71-74, 84, 90, 99, and 103.
The records of
X. corallipes make no distinction as to the subspecies
observed.
This species overwinters as a nymph and appears as
an adult early in the spring.
Scattered individuals were
found until mid-August but, in general, the majority had dis­
appeared by mid-July.
Fall populations of newly-hatched
- 43 I
nymphs were in numbers greater than I per sq yd on some native
grassland sites but in lower numbers on abandoned fields.
It
was found in a variety of habitats but most commonly on sandy
areas of low-stature vegetation.
Both the nymphs and adults
were observed to feed on forbs and grasses.
However, feeding
on grasses was more common by nymphs than by the adults.
The
adults included more dry plant debris and forbs in their diet
but, in comparison to the nymphs, spent little time in feed­
ing.
ADDITIONAL RESULTS AND DISCUSSION
The preceding discussion has indicated a relationship
between the occurrence of most grasshopper species and their
known food-plant preferences.
Nevertheless, it was noted
early in the study that the observed distribution and abun­
dance of grasshoppers were influenced by factors beyond the
mere availability of food.
Grasshopper populations were generally low during the
period that the study sites were established.
Consequently,
it is realized that the grasshopper-vegetation relationships
observed and measured during this period of comparatively low
grasshopper numbers may be altered considerably during periods
of high populations.
The importance of time has been mentioned previously in
regard to the relationship between certain grasshopper species
TTT
- 44 -
life-histories and their presence or absence at the time a
study site was visited„
Grasshopper species abundance is
likewise related to the time of sampling.
This relationship
is brought out in the typical seasonal population curves of
Figure 3«
The data from which Figure 3 was established were
obtained in 1958 from a small area of less than 2 acres on
flat topography.
This study area was of comparatively uniform
vegetation consisting primarily of Stipa comata, Agropyroh
smithii, Bouteloua gracilis, Koeleria cristata, Poa secunda,
Garex eleocharis, and numerous forbs such as Artemisia
frigida, Sphaeralcea coccinea, Liatris punctata, and Vicia
sparsifolia.
Detailed studies of vegetation and the local
grasshopper distribution were made and will be presented in a
later paper.
For the purposes of the present paper, however,
it should be mentioned that the quantitative estimates of the
grasshopper populations present on the study area' were made by
use. of the "night cage" method of sampling.
The seasonal
variations in the grasshopper populations of this area are
typical of those measured in previous Montana studies which
employed the use of "night cages" (Anderson & Wright 1952,
Anderson 1961).
The wide differences in numbers measured
from one sampling time to the next result in part from using
a random sampling method when the distribution of grasshoppers
is not random.
This non-random distribution becomes particu­
larly evident in studies of local damage to vegetation
45
--
TOTAL
POPULATION
YAR
- MELANOPLUS
- AGENEOTETTIX
OEORUM
OUADRIMACULATUM
number
per
square
-- PHLIBOSTROMA
INFANTILIS
JULY
FIG. 3.
AUGUST
SEASONAL
POPULATION
FLUCTUATIONS
OF
ONE
AREA
IN
AS
| SEPTEMBER
THE
GRASSHOPPER
MEASURED
IN
1958.
(Anderson 1961) .
It may- be attributed to non-random plant
distribution and seasonal changes in the physical structure of
the vegetation.
An important point to note from Figure 3 is
the apparent rapid decline in grasshopper numbers soon after
the peak numbers are reached following hatching.
This.has
been recorded for every occasion in which "night cages" have
been used and cannot be attributed to grasshopper movement.
The absence of extensive local movement on the part of
most grasshopper species inhabiting an area has been demon­
strated indirectly by control measures which have effected
forage protection for more than one season on pastures sur­
rounded by high grasshopper populations (Anderson 1961).
More
direct evidence has come from two separate field experiments
involving marked adults.
The first experiment was conducted on a gently sloping
area dominated by Agropyron smithii and Stipa comata.
Six
plastic containers, lg" x 3 z " x 7", were buried to ground
level within a radius of I yd.
On 2? July i960 the containers
were filled with a bran bait which had been tagged with phos­
phorus -32.
The bran was kept moist and the grasshoppers were
allowed to feed upon it until 27 August i960 when the experi­
ment was terminated.
Grasshoppers captured by the "night
cage" method of sampling and by sweep-net collections both
on the baited and surrounding areas were monitored for radio­
activity.
- 47 During the month-long.sampling period most of the radio­
active grasshoppers captured were within 20 ft of the feeding
site.
Nine radioactive female Aulocara elliotti were col­
lected at greater distances.
Five of these were found within
100 ft, 2 between 140 and 160 ft, I at 200 ft, and I at 280
ft, from the feeding site.
One radioactive male A., elliotti
was obtained 112 ft from the feeding site.
Six radioactive
Helanoplus bilituratus females were found beyond 20 ft of the
feeding site.
ft.
Five of these were within 60 ft and I at 128
Three radioactive M. bilituratus males were encountered
within 100 ft of the feeding site. Nine radioactive
Melanoplus packardii females were also found within 100 ft
of the feeding station.
males were captured.
Fifteen radioactive M. packardii
Five of these were within 100 ft, 7
between 100 and 180 ft, I at 305 ft, and I at 385 ft from the
bait.
Four radioactive Hadrotettix trifasciatus females were
collected beyond a 20 ft radius.
Three of these were between
60 and 80 ft, and I at 112 ft from the feeding site.
The only
radioactive H. trifasciatus male encountered was 68 ft from
the feeding station.
Two radioactive Melanoplus occidentalis
males were encountered more than 20 ft from the feeding site;
I at 40 ft and the other at 95 ft.
One radioactive Camnula
pellucida female was found 435 ft from the bran among other
£. pellucida females which had congregated on a small area
during oviposition.
—
I+B
—
The second experiment was conducted from 15 July - 20
August 1961 in a shallow basin of approximately 2 acres which
was dominated by Agropyron smithii.
In this experiment adult
Aulocara elliotti were marked with a non-toxic "locust
marking" paint manufactured by Imperial Chemical Industries,
Ltd., London.
During the experimental period some congre­
gation of adults was noted in the area.
No marked adults were
observed more than $0 yards from the point of release, with
the majority of the marked individuals remaining within a
radius of 20 yards. „In general it was noted that males were
found farther from the release site than were females.
The non-random distribution and limited movement of
grasshoppers are indications of some relationship existing
between vegetation composition and grasshopper distribution.
This relationship is not clear especially where numbers of
grasshoppers are concerned.
Gangwere (1961) has concluded
from his work on food selection by Orthoptera that "...food
probably plays only a minor part in the insects' habitat
selection".
From studies of Australian grasshoppers,
Andrewartha & Birch (1954, p. 592) state:
"The supply.of food
was therefore quite unrelated to the numbers of grasshoppers
and it cannot in any sense be construed as a ’density-depend­
ent factor*.”
Previous studies in Montana (Anderson & Wright 1952)
showed that all grasshopper species observed displayed a
- 49 -
certain amount of food-plant preference.
The degree of' selec­
tivity was found to vary greatly between species; some being
comparatively omnivorous while others are highly selective.
It could be assumed that the composition of vegetation may
play an important role in determining the local distribution
of grasshoppers.
Such was indicated in the discussion of
species occurrence and appears likely particularly where a
species is highly selective as to food-plants.
Such species
were found only where the composition of the vegetation
included their preferred food-plants.
On the other hand,
specific food-plants were often found in varying degrees of
abundance without those grasshopper species which prefer them
being present.
_
The composition of the vegetation also appears to have an
effect upon the distribution and abundance of those grass­
hopper species which are rather general grass- or forb-feeders
not limited in preference to a single plant or to a few plant
speciesi
Numerous observations on grasshopper populations
have shown the grass-feeding as well as forb-feeding species
’ "s: ■
to be most abundant in areas where their preferred foods were
readily available.
These observations have been substantiated
by the data presented in Tables II and III.
In general, the grass-feeding species listed in Table II
were most numerous where perennial grasses comprised more than
1+0% of the vegetation.
The appearance of such forb-feeders as
TABLE II.
Per cent frequency of occurrence of grasshopper species in numbers
greater than I per sq yd on Native Grassland Study Sites.
0-20
* Aeropedellus claVatus
* Agehedtettix"deorum
* -Amphitornus coloradus
* Aulocara elliotti
* Bruneria brunnea
* Drepanopterna femoraturn
** Hesperotettix viridis
*** Melanoplus bilituratus
■***Melanoplus cohfusus
** Melanoplus dawsoni
Melanoplus infantilis
*** Melanoplus occidentalis
Melanoplus packardii
* Metator pardalinus
* Opeia obscura
* Phlibostroma quadrimaculatum
* Phoetaliotes nebrascensis
* Trachyrhachis kiowa
*** Trimerotropis campestris
Xanthippus corallipes
* Primarily grass-feeding species
'I'* Primarily forb-feeding species
*** Mixed-feeding species
50
21-40
33
17
50
50
17
17
17
17
17
41-60
’ 50
25
13
25
13
13
13
38
25
13 .
■13
13
13
61-80
■
18
24
18
18
6
6
6
12
6
35
12
12
6
18
6
9
6
81-100
25
30
20
15
15
10
10
5
50
10
10
15
90
15
15
TABLE III.
Per'cent"frequency of occurrence of grasshopper'species in numbers
greater than I per sq yd on Abandoned Field Study Sites.
■ Perennial Grass-Cover Classes, in %
81-100
41-60
61-80
21-40
0-20
*
*
*
*
*
***
Aeropedellus clava'tus
Ageneotettix deorum
Amphibornus coloradus
Aulocara ellidtti
Camnula pellucida
Melanoplus bilituratus •
Melanoplus bivittatus
•**Melanoplus infantilis
*** Melanoplus occidentalis
** Melanoplus packardii
33
17
100
40
33
100
17
' 67
50
20
80
20
■ 67
67
33
. 33
17
50
20
33
* Primarily grass-feeding species
** Primarily forb-feeding species
*** Mixed-feeding species
100
- 52 -
Hesperotettix viridis and Melanoplus packardii in the higher
classes of perennial grass-cover can also be explained on the
basis of the feeding habits of these 2 species.
H. viridis
was restricted primarily to Gutierrezia sarothrae and M.
packardii to members of the Leguminosae occurring on native
grasslands.
The abundance of Aeropedellus clavatus and
Melanoplus occidentalis in the low-percentage perennial grasscover classes is not so easily explained in light of their
,observed feeding habits.
Both appear to prefer grass although
M. occidentalis has also been observed to feed on forbs.
Pos­
sibly the presence of A. clavatus may be explained most easily
on the basis of availability of green succulent grass early
in the season when this early-hatching species is most abun­
dant.
The appearances of the remaining species listed in
Table II are in accord with their observed feeding habits.
As is shown in Table III, the number of species found to
comprise the dominant grasshoppers on abandoned fields was
relatively small.
In accord with observed grasshopper feeding
habits, fields which had been abandoned for several years and
had reverted to a point of dominance by perennial grasses were
those which harbored the highest populations of the grassfeeding species.
Conversely, those abandoned fields in the
earlier stages of plant succession in which annual or peren­
nial forbs and annual grasses were dominant (the 2 lowest per­
ennial grass-cover classes) harbored the highest populations
- 53 -
of forb-feeding species.
It should be noted, however, that 3
species considered to be grass-feeders were found among the
dominants of the 2 lowest perennial grass-cover classes.
As has been pointed out, Ageneotettix deorum is a grassfeeding species which apparently displays no preference for
any particular grass.
It has been shown that it also devours
large quantities of dry plant debris which is found on the
ground.
With the possible exception of fallen grass seeds,
no particular component of the debris seems to be preferred.
This debris-feeding habit may, therefore, be responsible for
the widespread distribution of A., deorum both on abandoned
fields and native grasslands.
The distribution of the other two grass-feeding species
on recently abandoned fields was found to be definitely asso­
ciated with areas of preferred food-plants.
Aulocara elliotti
was found in patches of Agropyron smithii or, on some older
fields, Agropyron cristatum.
with Poa pratensis.
Camnula pellucida was associated
It was observed that P. pratensis often
accounted for only a very small percentage of the total vege­
tation of an abandoned field.
It invariably grew in small,
dense patches varying in size from a few to several hundred
square feet.
It was within these localized areas that C .
pellucida was found.
Usually this species had eaten the P.
pratensis nearly down to ground level and it was on these
heavily damaged, heavily sodded areas that aggregations of C.
- 54 -
pellucida were found during mating and oviposition.
One may note from the above discussion that it has been
possible to relate grasshopper distribution and abundance, to
some degree, with the availability of specific food-plants.
Again it should be pointed out that these specific food-plants
may be present in varying amounts without those grasshopper
species which prefer them being present.
In other words,
something beyond the mere availability of food appears to be
involved in both habitat selection and abundance of grass­
hoppers on Montana grasslandsi
In a review of the "factors affecting food selection in
Orthoptera, Gangwere (1961) has stated:
"Climate, as well as
microclimate, exert an influence on the feeding behavior of
Orthoptera.
Air and ground level heat, humidity, and wind act
separately and together, both on the feeding insects and on
the vegetation or animals on which they feed.
The effects of
these agents are modified by features of the topography and by
density of .the plant cover, which determine the degree to
which the insects are sheltered."
No measurements of the
modifying effects of plant cover on the microclimate were made
in the present study. Numerous opportunities, however, arose
during this study to compare the numbers of grasshoppers on
grassland grazed by livestock during the spring and summer
with the numbers in an adjoining pasture which was grazed dur­
ing the winter only.
The amount of bare ground in each
- 55 -
pasture was often nearly the same but invariably the height of
the vegetation in the winter pastures was greater; i.e., more
ground was shaded.
Grasshopper populations were generally
found "to be inversely proportional to the plant height and
amount of shading.
The relationships between grasshopper
populations and measurements of total foliage cover of the
study sites .tend to substantiate these observations (Table
IV).
Total foliage cover, as measured on the study sites, is
in effect an estimate of the amount of shade cast by the vege­
tation.
As is indicated by the data presented in Table IV,
grasshopper populations on native grassland sites were found
to occur less frequently where the per cent total foliage
cover was greater than 40.
Although some species are listed
under total foliage-cover classes greater than 40%, it should
be noted that they were in low- numbers and barely qualified
/
under the "greater than I per sq 'yd" category.
It should- also
be pointed out that the abundance of grasshoppers never
exceeded I per sq yd in areas dominated by either Artemisia
tridentata or Sarcobatus vermiculatus during observations over
the 12 years covered by this study.
Three species which were always found in numbers too low
to qualify for inclusion in Table IV were Chorthippus longicornis. MeIanoplus montanus, and Neopodismopsis abdominalis.
It is of interest that these species occurred in mountain
TTTTT
TABLE I V . Per cent frequency of occurrence of grasshopper species in numbers
greater than I per sq yd on Native Grassland Study Sites.
■- Total Foliage-Cover Classes, in $
0-20
Aeropedellus clavatus
Ageneotettix deorum
Amphitornus cbloradus
Aulocara ellibtti
Bruneria brunnea
Drepanopterna femoraturn
Hesperotettix viridis
Melanoplus bilituratus
Melahoplus cohfusus
Melanoplus dawsbrii
Melanoplus infantilis
Melanoplus oceidentalis
Melanoplus packardii
Metator pardalinus
Opeia obscura
Phlibostroma quadrimaculatum
Phoetaliotes nebrascensis
Trachyrhachis kibwa "
Trimerotropis campestris
Xanthippus corallipes
30
33
17
27
3
13
7
17
13
7
47
17
7
10
10
33
10
17
3
21-40
41-60
25
25
42
8
8
13
25
8
13
'
25
25
17
61-80
13
13
13
17
17
8
8
13
13
13
81-100
-
57
-
meadows where the total foliage cover always .exceeded 60%, ■
The relationship between grasshoppers occurring on aban­
doned fields and the total foliage cover is not as evident as
on the native grassland sites.
Those species listed in Table
V appeared to be affected to a greater extent by the composi­
tion of the vegetation on abandoned fields than by the total
foliage cover.
At each of the study sites a measurement of the amount of
ground covered by litter was made.
The. results of attempting
to relate the presence of grasshoppers to the amount of litter
will be found in Tables VI and VII.
It was noted that there
was usually a direct correlation between the amount of ground
covered by litter and the total foliage cover.
Therefore,
with the possible exception of Ageneotettix deorum and
Melanoplus bilituratus. 2 species which devour large quan­
tities of dry plant debris, it is not possible to point to any
direct effects which the amount of litter may have on grass­
hopper species distribution or abundance.
It is generally recognized that the vegetation of grass­
land areas has been and continues to be modified or replaced
either in its entirety or in part.
These changes nearly
always appear to be the result of a disturbance by man or
domestic animals through cultivation or the practice of
grazing, in combination with the prevailing climatic condi- ■
tions.
TTT
Such changes in vegetation have been considered by a
TABLE V. ' Per cent" frequency of occurrence of grasshopper species in numbers
greater than I per sq yd on Abandoned Field Study Sites.
0-20
Aeropedellus clavatus
Ageneotettix'deorum
Amphitornus colbradus
Aulocara ellidtti
Camnula pellucida
Melanoplus bilituratus
.Melanoplus bivittatus
Melanoplus infantilis
Melanoplus oc-cidentalis
Melanoplus packardii
25
25
50
25
50
25
25
25
50
Total Foliage-Cover Classes, in %
21-40
41-60
61-80
81-100
17
33
100
25
17
33
83
33
25
33
25
50
25
50
25
100
TABLE'VI.
Per cent frequency of occurrence of grasshopper species in numbers
greater than I per sq yd on Native Grassland Study Sites.
Litter-Cover Classes, in %
0-20
Aeropedellus clavatus
Ageneotettix deorum
Amphitornus coloradus
Aulocara elliotti
Bruneria brunnea
Drepanopterna femoratum
Hesperdtettix viridis
Melanoplus bilituratus
Melanoplus confusus
Melanoplus dawsoni
Melanoplus infantilis
Melanoplus occidentalis
Melanoplus packardii
Metator pardalinus
Opeia obscura
Phlibostroma quadrimaculatum
Phoetaliotes nebrascensis
Trachyrhachis kiowa
Trimerotropis campestris
Xanthippus corallipes
26
36
7'
29
13
7
16
10
3
39
19
7
7
10
29
7
16
3
21-40
29
14
21
7
14
14 .
14
7
21
14
7
7
7
7
41-60
61-80
81-100
100
20
40
20
40
40
40
20
20
20
20
20'
20
50
TABLE V T I . Per cent frequency of occurrence of grasshopper"species in numbers
greater than I per sq yd on Abandoned Field Study Sites.
Litter-Cover Classes, in %
21-40
41-60
61-80
0-20
Aeropedellus clavatus
Ageneotettix deorum
Amphitornus coloradus
Aulocara ellibtti
Camnula pellucida
Melanoplus bilituratus
Melanoplus bivittatus
Melanoplus infantilis
Melanoplus oceidentalis
Melanoplus packardii
81-100
33
33
50
33
50
17
33
33
67
33
33
' 50
100
33
17
33
33
33
17
50
'
33
67
100
67.
33
-
'61
-
number of investigators to be of extreme importance from the
standpoint of increases in grasshopper populations in many
areas.
The importance of abandoned land as a possible source of
grasshopper infestations has been recognized by various
workers (Fletcher 1902, Ball 1937, and others).
In fact,
weedy abandoned land was pointed to (Parker et al. 1955) as
one of the factors responsible for the upsurge of Melanoplus
bilituratus in the Great Plains area from 1934 to 193&.
Shotwell (1953) summarized the situation thus:
"In the
Dakotas in the thirties when one-third of the wheat was taken
out of production, this species built up to the biggest out­
break of grasshoppers seen in modern times."
The effect of heavy livestock-grazing on grasshopper
populations in the grasslands of British Columbia has been
studied by Treherne & Buckell (1924) and was recognized
earlier by Buckell (1921).
He states:
"At the. time when the
Riske Greek range was covered with Bunch-grass, and in fact,
up until the last few years when the increase in cattle and
horses has kept the range continually eaten down, the grass­
hoppers were never in sufficient numbers to be noticed by the
settlers.
Several of the older ranchers claim that grass­
hoppers were not present on the ranges in the early days, but
have come suddenly during the last few years.
There is little
doubt that this statement in its substance is incorrect.
It
- 62 is probably that all the injurious species, now found, were
present in the years gone by, but in far smaller numbers and ■
have only increased but slightly from time to time."
From his observations in England, Clark (194$) says that
grasshoppers are "...significantly influenced by the effects
of common methods of agriculture on soil and vegetation; dis­
turbance of soil by ploughing, or various types of grazing are
important factors determining their occurrence, and the most
favorable habitats observed here have been agriculturally
derelict or useless land.
Abundance of grasshoppers on agri- •
cultural land in this country, as in others, is an index of
poor soil or of poor farming, though here it does not carry
the penalties of mass outbreaks that it may do elsewhere."
Overgrazing has been pointed to as an important factor
in the creation of optimum habitat conditions for the increase
of grasshoppers in Russia (Bei-Bienko 1930, Rubtzov 1932,
1933)o
Many workers in this country (Branson 1942, Coyner
193$, 1939, Dibble 1940, Parker 1937, Smith 1940) have asso­
ciated an increase in grasshoppers with heavy grazing by live­
stock.
The major portion of this study has been concerned
primarily with the existing vegetation as it was encountered
at the time a particular area was visited.
In addition, year
to year vegetation changes were measured on a large wintergrazed pasture of the OW Ranch in southeastern Big Horn
- 63 -
county.
The topography and vegetation of this area have been
described previously by Anderson & Wright (1952).
The data
(Table VIII) were collected.from 4'permanent quadrats, each I
sq meter in area, which were examined yearly some time between
15 June and 30 June.
During the 8 years, changes in vegeta­
tion which were measured on these 4 quadrats appeared to be
typical of the observed changes over a vast portion of the
grazing lands in southeastern Montana.
Grasshopper popula­
tions on the study area, as well as in most of the south­
eastern part of the state, had dropped to less than I per s q .
yd by 1951 following a period of 4 years during which they
reached "outbreak" numbers.
When the 4 permanent quadrats
were established in 1953, the grasshopper populations were
below I per sq yd and remained at this low level until 196l.
In 1961 certain portions of the study area, and of south­
eastern Montana in general, again harbored populations greater
than I per sq yd.
The important point here is that, during
the period of low grasshopper numbers, great changes took
place in the composition and physical structure of the vege­
tation without accompanying changes in the number of grass­
hoppers present.
(See Table VIII)
It is concluded from the findings reported in this paper
and from field observations during the past 12 years that the
composition and physical structure of the vegetation on grass­
lands of Montana play an important role in the determination
TABLE VIII. Vegetation on 4 permanent square -meter quadrats at the OW Ranch >
Decker, Montana.
Total Number of Plants
or
**Total Basal Area (sq mm)
Quadrat" Number
and
Plant Taxa
I
Agropyron smithii
Alyssum alyssoides
Androsace sp".
Bromus japoriicus
'Camelina sativa
Helianthus ahnuus
Lappula redowskii
Lepidium perfbliatum
Plahtago purshii
Salsola kali
Tragopogon dubius
*1IiSchedonnardus paniculatus
**Sporobolus cryptandrus
1^ilI
iStipa comat a
II
Agropyron smithii
AlySsum alyssoides
Bromus japonicus
Carex eleocharis
Lappula redowskii
Polygonum douglasii
Tragopogon dubius
Viola nuttallii
**Poa secunda
1I0IiStipa viridula
:1953
1954
1955
1956
195S
1959
I960
1961
644
96
455
2670
12
I
221
526
255
1400
50.6
2
660
155
374
9
172
9
11
6
2
4
3
39
I
I
5
7
14
13
5
I
2
90
-1
14
•I
19
1441
112
1032
602
S
IS
45
2
27
10
16
25
1115
4
2
643
1200
814
4
I
I
3
4
10
I
I
I
46
7
13
818
73
181
3
998
143
4
I
53
■ I
I
28
55
TABLE VIII.
(Concluded)
III
.....
Agropyrdri smithii
Bromus japonicus'
Calochortus aIbicaulis
Chenopodium sp.
Cryptanthe kelseyana
Festuca octifIora
Helianthus arinuus
Lappula reddwskii
Oenothera" albicaulis
Plantago purshii
Sysimbrium loeselii
Tradeseantia occidentalis
^Antennaria dimorpha.
**Bouteloua gracilis
**Poa secunda
**Stipa comata
■IV
-Agrdpyrori smithii
Alyssum alyssoides
Bromus japonicus
Carex eleocharis
Collinsia parviflora
Festuca octiflora
Lappula redowskii
Plantago purshii
Psoralea argophylla
Psoralea tenuiflora
Sphaeralcea coccinia
Sysimbrium loeselii
Tragopogon dubius
^i=Artemisia frigida
**Koeleria cristata
;!;*Poa secunda
**Stipa comata
1953
1954
1955
1956
1958
1959
I960
1961
15
34
B
2
39
223
20
.939
.39
276
43
7
2
I
2
I
2
17
I
I
20
19
5
395
I
20
13
7
290
14
244
220
213
93
5
. 66
I
3
I
7
6
694
66
4
2
61
I
109
14
I
I
' I
3
I
43
106
4
I
5
3
I
I
I
I
I
I
2
I
60
106
I
I
31
6
147
I
2 .
5
39
3
495
I
7
272
7
24
364
41
20
236
&
12
I
1
624
3
6
I
44
12
50
I
I
473
7
236
19
129
10
137
3
170
174
119
54
46
3
106
57
5
76
2
293
3
431
506
32
107
I
A
I
347
226
16
46
I
26
27
23
- 66 -
of areas of occupancy by grasshoppers.
It is concluded fur­
ther that the composition and structure of vegetation are not
responsible for initial grasshopper population increases or
declines.
This does not negate the importance of proper man­
agement of grazing lands as a deterrent to economic damage
from grasshoppers (Pepper 1955).
It does deny, however, that
vegetation changes resulting from land use, effects of cli­
mate, or both, are in and of themselves responsible for grass­
hopper "outbreaks".
The above conclusions are consistent with the observed
mosaic patterns of grasshopper distribution on grassland areas
'I
;
!
during periods of high as well as low population numbers.
j
These conclusions are also consistent with the findings that
grasshoppers were often absent from habitats which appeared
to be particularly favorable to them from the standpoint of
vegetation.
Above all, these conclusions are consistent with
a concept which recognizes the grasshopper population as a
dynamic variable which is not merely a pawn of its external
;
environment.
SUMMARY •
The general distribution of 65 grasshopper species on
the grasslands of Montana east of the Rocky Mountains is
recorded and discussed.
Detailed studies of grasshopper-
vegetation relationships were made on 105 native grassland
L
- 67 ■and abandoned field sites.
Measurements of vegetation
including taxonomic composition, basal cover, foliage cover,
and the amount of ground covered by litter were.made at each
study site.
Accompanying grasshopper population densities
were estimated and the species present were recorded.
Time as a factor influencing the results of this study
is discussed with regard to grasshopper life-histories and
changes in population density during a season.
Two field
experiments involving marked individuals are described.
These
indicate that grasshopper movement is not an important factor
in seasonal changes of a population on a particular area.
The following conclusions resulted from this study:
1.
The taxonomic composition of the vegetation, as related to
feeding-habits, is important in determining the local dis­
tribution and abundance of most grasshoppers.
2.
The physical structure o£ the vegetation is important in
determining the local distribution and abundance of most
grasshoppers.
The highest populations were found where
the per cent total foliage cover was below 40.
3•
The amount of ground covered by litter has little or no
effect on local grasshopper distribution and abundance.
4.
Vegetation plays an important role in the selection of
areas of occupancy by grasshoppers within a grassland
habitat but is not a causative agent responsible for
initial changes in grasshopper abundance.
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Andrewartha, H. G. & L. C . Birch.
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