Beef IQ:
Biology and Management of Horn
Flies and Face Flies
Kelly Loftin
Associate Professor/Extension Entomologist
Department of Entomology
Fayetteville, Arkansas
479 575-3462
kloftin@uaex.edu
Livestock Pests - Flies
 “Pasture”
breeding flies
– Horn Fly
– Face Fly
 “Premise”
breeding flies
– House Fly
– Stable Fly
 Black
flies or Buffalo Gnats
 Biting Midges
 Horse Flies
Family Muscidae
Horn Fly
Haematobia irritans
Horn Fly – Economic
Importance
Most economically important insect pest of
pastured cattle in the U.S.
 Losses occur through blood loss and annoyance,
infestations of up to 10,000 flies per animal have
been documented.
 Losses in cow-calf production is an indirect
reduction in calf weaning weight. Reduction in calf
weaning weights vary from 18 pounds and up.
 Stocker cattle gains may be reduced by 50
pounds.
 Linked to increased summer mastitis in cattle

Horn Fly - Life Cycle & Biology
Haematobia irritans
 Complete
metamorphosis
 Adult remains on host
- except for egg
laying.

Horn Fly - Life Cycle & Biology
Adults live from 6 - 8 weeks,
mating occurs on the host
about 3 days after
emergence.
 Eggs laid on fresh cattle
manure, less than 10 minutes
old
 Larvae develop in manure.
 Horn flies overwinter as
pupae in the soil.
 Life cycle from egg to adult is
from 9 - 12 days.

Two Seasonal Peaks in Abundance
350
300
250
200
150
100
50
0
March
April
May
June
July
August Sept.
Oct.
Nov.
Horn Fly Management
Return of $ 2-5, for each $ 1 spent.
 Treat when population reach an average of
200 per animal for beef cattle (100 for dairy
cattle).
 Dust bags, back rubbers, mechanical traps.
 Mineral/feed additives (IGR’s –methoprene,
diflubenzuron; Larvicides - tetrachlorvinphos).
 Sprays, pour-ons, dusts.
 Insecticide impregnated ear tags.

Economic Thresholds and Counting
Horn Flies
Economic injury level is 150-200 flies per animal
(75-100 dairy).
 Count flies on a minimum of 10 animals to obtain
an average.
 Whole body, one side, two sides? Whole animal
counts are more accurate but not always possible.
 When flies are less than 25 per animal count
individually, when greater than 25 count in
multiples of 5, 10, etc.

b
a
Drawings of estimated
population of horn flies on
cattle; a = 50, b = 100 and c =
200.
c
Horn flies on bull and belly of Hereford.
Control Methods
Horn fly (Bruce) trap
Passive, no
chemicals
 Restrict access to
feed or water
 Animal must pass
through trap
 Up to 70% control
 Cost (material):
$500-550

Potential Issues with Trap
 Trap
maintenance (horned cattle)
 Alternate water sources (rainfall and wet
weather water sources)
 On occasion individual animals will not
pass through trap
Horn Fly Demonstration – Dallas County
250
Treatment threshold
200 per animal
Average horn flies per animal
200
150
Trap
Control
100
50
Cattle moved to
another pasture
Date
4
00
23
/2
9/
9/
16
/2
00
4
04
9/
20
04
9/
8/
9/
2/
20
4
26
/2
00
4
00
19
/2
8/
8/
12
/2
00
4
04
8/
5/
20
4
00
29
/2
7/
7/
22
/2
00
4
0
Insecticide Impregnated Ear Tags
One treatment ? If not
applied too early
 Organophosphates,
pyrethroids,
organochlorines and
now macrocyclic
lactone (abamectin)
 Insecticide resistance
should be considered
 Insecticide classes
should be rotated

Horn Fly Demonstration – Stone County
400
350
Average horn flies per animal
300
250
Treatment threshold
200 per animal
Control
Ear Tag*
200
Backrubber**
*One Avenger ear tag
per animal.
**Backrubber charged
with permethrin and
diesel
150
100
50
0
8/21/2006
8/28/2006
9/4/2006
9/11/2006
9/18/2006
Date
9/25/2006
10/2/2006
10/9/2006
Ear tag Insecticide classes
Insecticide Class
Beef Dairy*
Synthetic Pyrethroid
Yes
Yes
Organochlorine**
Yes
No
Organophosphate
Yes
No
Macrocyclic lactones
Yes
Yes
* Lactating dairy cattle.
** Existing stock only (Avenger), no longer manufactured.
Remember to rotate insecticide classes and remove tags
when they become ineffective or at the end of the fly
season to lessen insecticide resistance or tolerance issues.
Backrubbers and Dust Bags
Self treatment device
 Recharge when needed
 Backrubber is saturated
with a light oil solution
containing insecticide
 Dust bags are closed
mesh burlap bags
containing insecticide
dust – no mixing
necessary
 Best if forced use

Paired, forced-use dust bags
Forced-use backrubber
Issues with Backrubbers and Dust Bags
 Are
the animals using the self-treatment
device?
 Forced-use deployment is best (restrict
access to feeders, etc.)
 Maintenance and charging
IGR’s and Larvicides
Insecticide mixed into trace minerals formulated
as a block, as granular form mixed with feed, or
as liquid feed
 Consider proximity to untreated animals
 Kills horn fly larva developing in manure
 Animals must eat a specified amount each day
 Examples: IGR’s - Altosid (methoprene) and
ClariFly (diflubenzuron). Larvicides – Rabon
(tetrachlorvinphos)

A small amount of insecticide
is poured down the backline
 Rates vary ~ about ½ ounce
maximum
 Higher insecticide
concentration than sprays (310%)
 Two types: traditional
insecticide and endectocide
 Endectocide pour-ons control
internal parasites, lice and
horn flies, consider horn fly
control as an added benefit

Pour-ons
Endectocides for horn fly control?
Ivomec, Cydectin, etc. Pour-ons
 Cost of endectocide pour-ons are decreasing
especially with generics.
 Probably best not to rely on endectocides alone
to control horn flies (use when necessary for
internal (worms) parasites). Label excerpt
…should be a part of the parasite control
program for both internal and external
parasites.
 Ivomec pour-on will control horn flies from 1428 days, meaning multiple applications may be
required during a fly season.

Sprays
Controls adult flies, ticks, lice
 High pressure sprays to apply a
large volume of insecticide solution
(1-2 quarts)
 Low-volume sprays apply about 2
ounces per animal, uses nozzles
set up in gate or doorway where
animal must pass

Walk through
sprayer
Restrict access to
minerals or water
 Animals are
automatically treated as
they pass through
(electronic eye)
 Not to be continuously
operated – operate only
when fly numbers reach
treatment threshold
 Commercial units are
available

Solar powered automatic sprayer
Horn fly demonstration – Washington County
700
600
400
Treatment threshold
200 per animal
Automatic sprayer*
Control
300
*Charged with permethrin
(2 oz. Permethrin-10 per
gallon water)
200
100
Date
10/18/2006
10/11/2006
10/4/2006
9/27/2006
9/20/2006
9/13/2006
9/6/2006
8/30/2006
8/23/2006
8/16/2006
8/9/2006
8/2/2006
7/26/2006
7/19/2006
0
7/12/2006
Average horn flies per animal
500
Issues with automatic sprayer
Are the animals using the sprayer? Similar
issues with back rubbers, dust bags and trap.
 Restrict access to minerals or water (forced
use).
 Individual animals may not use the sprayer
(observe).
 Cattle should be acclimated to sprayer.
 Inert ingredients (xylene) in some insecticide
formulations will damage pump. Most animal
insecticides work fine (exception: Ravap, but
formulation may be changed to remove xylene).

http://www.uaex.edu/Other_Areas/publications/PDF/FSA-7031.pdf
Consult MP 144 “Insecticide Recommendations for Arkansas”
which is updated yearly.
http://www.uaex.edu/Other_Areas/publications/HTML/MP-144.asp
Read and follow the insecticide label.
Family Muscidae
Face Fly
Musca autumnalis
Face Fly – Economic Importance
Musca autumnalis
 Introduced into North America in 1952, native
to Europe, China, North Africa, etc.
 Economic losses from decreased weight gain,
decreased milk production, and mechanical
transmission of pinkeye
 Does not reach pest status every year in
Arkansas, usually only a major problem 1 or 2
years out of every 5 years. More of a pest in
north Arkansas than south Arkansas

Face flies on cow (left) and calf infected with
pinkeye (right).
Face Fly
Face Fly Biology
Intermittent feeders
 Females feed on
secretions around the
eyes and on saliva
(ptotein for egg
production)
 Female and Male feed on
nectar and pollen
 Once feeding is complete
the female leaves the
host

Adult female lays eggs
on fresh cattle manure
 Eggs hatch into larvae
 Larvae develop in the
manure
 Larvae pupate in soil
near manure pat
 Adults emerge from
pupae (white)
 Life cycle from egg to
adult is from 11 - 17
days
 Overwinter as adults

Face Fly Life Cycle
Face Fly Management
Face fly are difficult to control because they are found
on the face (hard to treat area) and spend little time
on the host.
 Insecticide treatment may be necessary when an
average of 10 flies per animal (face) are present.
 Face flies are equally attracted to adult cattle and
calves.
 Self treatment devices (back and face rubbers, dust
bags, face misters) provide control.
 Insecticide impregnated ear tags provide limited
control (pyrethroid ear tags (2 per animal) are
generally more effective for face flies than the
organophosphates).

Consult MP 144 “Insecticide Recommendations for Arkansas”
which is updated yearly.
http://www.uaex.edu/Other_Areas/publications/HTML/MP-144.asp
Read and follow the insecticide label.