1. Beef IQ: Biology and Management of Horn Flies and Face Flies
Kelly Loftin
Associate Professor/Extension Entomologist
Department of Entomology
Fayetteville, Arkansas
This presentation will provide information on the biology and control of horn flies and face flies. My contact information is provided if you have questions about other livestock or poultry pests.

2. 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
Several species of flies can be important cattle pests; but, we will concentrate on horn flies and face flies.
House and stable flies are more of an issue around animal housing and feeding areas.
Black flies, horse flies and biting midges can be pests in localized areas with certain aquatic habitats.

3. Family Muscidae Horn Fly Haematobia irritans
The scientific name for the horn fly is Haematobia irritans.

4. This picture shows horn flies feeding on a bull
This picture shows horn flies feeding on a bull. In this example, horn fly numbers exceed the treatment threshold.

5. 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
The horn fly is the most important economically insect pest of pastured cattle in US
Losses occur through blood loss and annoyance, infestations of up to 10,000 flies per animal have been documented
In cow-calf production, losses are indirect reductions in calf weaning weight
Reductions of 18 pounds in calf weaning weights have been reported if flies are left untreated (these are conservative estimates).
Some studies have shown that stocker gains can be reduced by 50 pounds if flies are left untreated.
Horn flies are also linked to summer mastitis in cattle (especially dairy cattle).

6. Horn Fly - Life Cycle & Biology
Haematobia irritans
Complete metamorphosis
Adult remains on host - except for egg laying.
Adult horn flies remain on host all time except for egg laying. Both sexes take blood meals.
Like all flies, horn flies exhibit complete metamorphosis with very distinct eggs, larvae (maggots), pupae and adults.

7. Horn Fly - Life Cycle & Biology
Adults live from 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 days.
Adult horn flies will live from weeks, mating occurs on the host about 3 days after emergence
Both sexes take blood meals.
Eggs are laid on fresh cattle manure, less than 10 minutes old, larva develop in manure
The life cycle from egg to adult takes from days during optimal environmental conditions.
Horn flies survive the winter as pupae (the stage between larvae and adults) in the soil.

8. Two Seasonal Peaks in Abundance
In Arkansas two seasonal population peaks occur – Spring and Fall. Horn fly populations normally decline in the hot and dry period of summer but become abundant again in the fall as rain and humidity increases. Often the fall peak is much greater than the spring peak.

9. 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 studies demonstrate a return of $ 2-5, for each $ 1 spent on horn fly control.
When the average number of flies reach for beef cattle; or for lactating dairy cattle, treatment is recommended to prevent economic losses.
For IGR (insect growth regulators) or feed additives to be effective they should be started soon after horn flies appear in the spring because IGR’s do not kill adults flies.
Control methods include: dust bags, back rubbers, mechanical traps, mineral/feed additives, sprays, pour-ons, dusts, and
insecticide impregnated ear tags.

10. Economic Thresholds and Counting Horn Flies
Economic injury level is flies per animal ( 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.
Monitoring horn fly abundance is an essential component of your management program.
Count flies on a minimum of 10 animals to obtain a herd average.
Should you make whole body, one side or two sides counts? Whole animal counts are more accurate but are often not possible. Counting both sides of the animal may provide a more accurate estimate than counting the one side, but counting one side still provides a good indication of horn fly abundance.
When flies are less than 25 per animal counting is easy, when numbers are greater than 25 count, it is best to count in multiples of 5, 10 or 25, etc.

11. a b
Drawings of estimated population of horn flies on cattle; a = 50, b = 100 and c = 200.
In this drawing, cow A has about 50 flies, mostly on the withers. Cow B has about 100 flies, mostly from the withers downward. Cow C has over 200 flies, with flies from the withers down to the shoulder, on the belly, head and legs. c

12. Does this animal have more than 200 horn flies? Yes

13. Horn flies on bull and belly of Hereford.
Note that horn flies are often found on the belly and are difficult to count.
Horn flies on bull and belly of Hereford.

14. Control Methods

15. Horn fly (Bruce) trap Passive, no chemicals
Restrict access to feed or water
Animal must pass through trap
Up to 70% control
Cost (material): $
Trapping is one method. The passive horn fly trap dislodges horn flies as the animal passes through the trap. Dislodged flies are trapped in the trapping elements located on the sides of the trap. The animals must pass through the trap to provide control. Traps are usually located so that the animals must pass through it to gain access to water. In one Arkansas trial, an overall reduction of 57% was noted when compared to an untreated herd. In another trial, a 50-75% reduction in frequency of insecticide applications occurred.

16. In this slide, dairy cattle pass through a horn fly trap
In this slide, dairy cattle pass through a horn fly trap. At the time this picture was taken the trap had been in place approximately one week. In this example, the cows pass through the trap twice per day and in on direction only. In most beef operations the traps is operated in both directions.

17. 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
Walk through traps must be properly maintained and used to obtain effective control. Potential issues with walk through traps are:
Horned cattle may damage trapping elements.
Rainfall and wet weather water sources will allow cattle to water elsewhere and may not use the trap.
On occasion, individual animals will simply not pass through trap

18. Horn Fly Demonstration – Dallas County
In this trial, horn fly populations on the herd using the trap remained below treatment threshold.

19. 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
Ear tags can provide from 12 to 20 weeks of control. If after tagging, horn fly abundance does not decline within a few weeks, insecticide resistance may be a problem. Insecticide ear tags contain either organophosphate, pyrethroid, organochlorine or macrocyclic lactone insecticides or a mixtures. Some ear tag formulations also contain a synergist (piperonyl butoxide) that makes the insecticide more active. Insecticide resistance can be managed by rotating the insecticide classes. For example, if a producer has been using a pyrethroid ear tag for a year or two they should switch to a organophosphate, organochlorine or macrocyclic lactone the next year. Another option in managing insecticide resistance is to use another entirely different control method.

20. Horn Fly Demonstration – Stone County
The herd tagged with the endosulfan ear tag (Avenger) remained well below the treatment threshold when compared to the control and backrubber herds. Unfortunately, the endosulfan tag was discontinued…. But existing stocks may be available for a short period of time.

21. Ear tag Insecticide classes
Beef
Dairy*
Synthetic Pyrethroid
Yes
Organochlorine** No
Organophosphate
Macrocyclic lactones
* Lactating dairy cattle.
** Existing stock only (Avenger), no longer manufactured.
Remember to read the label before purchasing tags. Not all tags registered for use on beef battle are approved for use on dairy cattle. In addition to rotating tags, remove tags at the end of the fly season or when they become ineffective.
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.

22. 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
Backrubbers or dust bags can be very effective in managing horn flies if they are properly used and maintained. Dust bags and back rubbers do not have to be continually “charged” with insecticide and can even be temporarily taken down when horn fly abundance declines. With effective monitoring, these self treatment devices can be used when needed. In most cases, forced-use is required. This is accomplished by placing the self-treatment device in a gateway that the animals must pass through to gain access to feed or mineral ,etc.

23. Paired, forced-use dust bags
Dust bags are more effective if used in pairs, spaced to treat both sides of the animal.

24. Forced-use backrubber
A forced use backrubber placed in a gateway.

25. 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
As mentioned earlier, backrubbers and dust bags are more effective if animals are forced to use them. Both must be be properly maintained (charged with insecticide, etc.)

26. 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)
IGRs (which are insect growth regulators) and larvicides only kill the larvae developing in the manure. For IGR feed additives to be effective, the specified amount must be consumed daily. Proximity to untreated cattle is another consideration when using IGR’s. For example, if untreated animals are near an IGR treated herd, horn flies can migrate onto the IGR treated cattle and increase horn fly abundance.
For optimal effectiveness, IGR’s should be used soon after flies appear in the spring.
Examples are Rabon, Altosid (methoprene) Moorman’s & Pilgrim’s, Clarifly (diflubenzuron)

27. Pour-ons A small amount of insecticide is poured down the backline
Rates vary ~ about ½ ounce maximum
Higher insecticide concentration than sprays (3-10%)
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
Pour-on insecticides are ready to use and applied at higher concentrations that insecticide sprays.
Application rates vary but normally about ½ ounce per 1000 lb BW is applied
Some pour-ons (Cydectin, Ivermectin, etc.) also control internal parasites
Application is easy ….a small amount of insecticide is poured down the backline

28. 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 days, meaning multiple applications may be required during a fly season.
Think of endectocides as products that are used for controlling internal parasites. Think of horn fly control as only an added benefit of the endectocide application.

29. 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
Insecticide sprays control adult horn flies.
Generally, insecticide sprays can be used a couple of different ways: (1) high pressure , high volume sprays or (2) low pressure, low volume sprays. High pressure sprays apply a large volume of insecticide solution (1-2 quarts per animal)
Low-volume sprays apply about 2 ounces per animal and uses nozzles set up in gate or doorway where animal pass

30. 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
Walk-trough sprayers operate similar to dust bags, back rubbers and traps in that access to minerals or water is restricted.
Animals are automatically treated as they pass through (activated by an electronic eye).
Not to be continuously operated – operate only when fly numbers reach treatment threshold

31. Solar powered automatic sprayer
Here is an example of a commercially available solar-powered automatic sprayer

32. Horn fly demonstration – Washington County
In this example with the exception of one week, horn fly populations on the herd using the walk through sprayer charged with permethrin, remained below treatment level. The arrows indicate when the sprayer was operated.

33. 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).
Potential issues with the automatic sprayer are:
Are the animals using the sprayer? Similar issues with back rubbers, dust bags and trap.
Individual animals may not use the sprayer.
Cattle should be acclimated to sprayer before it is turned on.
Inert ingredients (such as xylene) in some insecticide formulations will damage pump.

34. For more information on horn flies consult this fact sheet, available in county offices or on the web.

35. Consult MP 144 “Insecticide Recommendations for Arkansas”
For current insecticide recommendations, consult the latest Insecticide Recommendations for Arkansas (which is updated yearly); also available at the county office or on the web.
Consult MP 144 “Insecticide Recommendations for Arkansas”
which is updated yearly.
Read and follow the insecticide label.

36. Family Muscidae Face Fly Musca autumnalis
The scientific name for the face fly is Musca autumnalis. This fly is closely related to the house fly.

37. 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
The face fly is another pest of cattle in Arkansas. In Arkansas, this fly does not reach pest status every year, usually it is only a major problem 1 or 2 years out of every 5 years. It is also more of a pest in north Arkansas than south Arkansas. This is related to their overwintering habits. Economic losses include decreased weight gain, decreased milk production, and mechanical transmission of pinkeye. Reduced weight gain and milk reduction is related to the annoyance factor that reduces animal grazing.

38. Face flies on cow (left) and calf infected with pinkeye (right).
This animal has about face flies feeding on secretions around the eyes, nose and face. The other animal has pink eye with can be spread by face flies. Mechanisms other than face fly feeding can also spread pink eye.
Face flies on cow (left) and calf infected with pinkeye (right).

39. Face Fly
This shows the relative size of the face fly. It is about the same size as a house fly but much larger than the horn fly.

40. 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
Face flies do not spend much time on the host; instead they feed intermittently on secretions around the eyes and nostrils. It is the female that feeds on secretions which she needs for egg production. Both sexes also feed on nectar and pollen.

41. Face Fly Life Cycle 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 days
Overwinter as adults
Adult females lay eggs on fresh cattle manure.
Eggs hatch into larvae that develop in the manure.
Mature larvae pupate in the soil near the manure pat.
Adults emerge from the pupae (which are a unique white color)
Life cycle from egg to adult requires from days
Face flies survive the winter as adults in protected areas but will become somewhat active on warms days during the winter. Face flies tend to overwinter better during winters with fairly constant temperatures than winters where we get warm days followed by sudden cold snaps.

42. 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).
Face flies are difficult to control because they are intermittent feeders that spend little time on the host; and because they are found on the face which is hard to treat. In the northeast US, face fly get so abundant that dairy producers in New York use exit type sprayers daily to mist the cow’s face as they leave the milking area. Insecticide sprays, ear tags and IGR’s will provide some control. Backrubbers equipped with face flyps and charged with permethrin do a pretty good job in controlling face flies.

43. Consult MP 144 “Insecticide Recommendations for Arkansas”
For current insecticide recommendations, consult the latest Insecticide Recommendations for Arkansas (which is updated yearly); also available at the county office or on the web.
Consult MP 144 “Insecticide Recommendations for Arkansas”
which is updated yearly.
Read and follow the insecticide label.