Acari
(ticks and mites)
Veterinary Entomology 208
Fall 2010
Acari facts
• 3 major currently recognized lineages:
 Opilioacariformes (spider-like mites)
 Acariformes (the “mite-like” mites)
 Parasitiformes (ticks and others)
• most diverse and abundant group of arthropods
• successfully colonized nearly every known
terrestrial, marine, and fresh water habitat
• most are very tiny (less than 1 mm); ticks are
exception
Ticks
Ticks to learn
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Argasidae
Argas persicus (fowl tick)
Otobius megnini (spinose ear tick)
Ixodidae
Ixodes scapularis (black-legged tick)
Haemaphysalis leporispalustris (rabbit tick)
Amblyomma americanum (lone star tick)
Amblyomma cajennense (cayenne tick)
Amblyomma maculatum (Gulf Coast tick)
Rhipicephalus sanguineus (brown dog tick)
Boophilus annulatus (cattle fever tick)
Dermacentor nitens (tropical horse tick)
Dermacentor albipictus (winter tick)
Dermacentor andersoni (Rocky Mountain wood tick)
Dermacentor variabilis (American dog tick)
capitulum and dorsal shield
Ixodidae
Argasidae
Argas persicus
Diagnostic features
• margin of body with
definite sutural line
• dorsal surface with
radiating lines of
‘discs’
Otobius megnini
Diagnostic features
• spider-like
appearance
• body of nymph
covered with spines
• early instars have 6
legs only
anal groove
distinct inverted ‘U’ in front
of anus
indistinct, behind
anus
Ixodes scapularis
other ticks
palp second segment
laterally produced into
conical projection
Haemaphysalis
leporispalustris
not produced
other ticks
palp second segment
twice as long as wide
about as long as wide
Amblyomma
other ticks
scutum ornation
a single posterior spot in
female
extensive
Amblyomma americanum
other Amblyomma
internal spur of coxa 1
half the length of external
spur
insignificant or absent
Amblyomma cajennense
Amblyomma maculatum
capitulum shape
hexagonal
quadrangular
(rectangular)
other ticks
Dermacentor
Rhipicephalus sanguineus
Diagnostic features
• palpi longer than
hypostome
• coxa 1 with 2 long
spurs
• festoons present, if
not engorged
Boophilus annulatus
Diagnostic features
• palpi shorter than
hypostome
• coxa 1 spurs very
small or absent
• festoons absent
palps
not overlapping hypostoma
overlapping hypostoma
Dermacentor nitens
other Dermacentor
spiracular plate
few, large goblet cells
many small goblet cells
Dermacentor nitens
other Dermacentor
spiracular plate
without dorsal prolongation
with dorsal prolongation
Dermacentor albipictus
other Dermacentor
spiracular plate
dorsal prolongation short,
wide
dorsal prolongation long,
narrow
Dermacentor variabilis
Dermacentor andersoni
Mites
Mites to learn
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Demodex spp.
Neoschongastia americanum
Dermanyssus gallinae
Ornithonyssus sylvarium
Psoroptes equi
Chorioptes bovis
Otodectes cynotis
Sarcoptes scabei
Notoedres cati
Psorergates simplex
Knemidocoptes mutans
body shape, legs
elongate, legs short
Demodex spp.
not elongate, legs medium
to long
other mites
body shape, legs
figure-8 body shape, 3 pairs
legs, lots of setae
body shape not figure-8, 4
pairs legs, few or no setae
larvae
adult
Neoschongastia
americanum
other mites
coxae
all close together
couplet 4
coxae 1 & 2 widely
separated from 3 & 4
couplet 5
anal plate shape, opening
plate not tapered posteriorly,
opening at bottom of plate
Dermanyssus gallinae
plate tapered posteriorly,
opening at top of plate
Ornithonyssus sylvarium
tarsal suckers, legs
suckers present, all legs long
couplet 6
suckers absent, all legs short
couplet 10:
Knemidocoptes mutans
tarsal sucker stalks
segmented
Psoroptes equi
unsegmented
other mites
legs 3 & 4
extending beyond margins of
body
couplet 8
not extending beyond
margins of body
couplet 9
(Sarcoptes scabei)
leg 3 setae of males
1 seta
2 setae
Chorioptes bovis
Otodectes cynotis
tarsal suckers of females
on legs 1, 2 & 4
on legs 1 & 2 only
Chorioptes bovis
Otodectes cynotis