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Don’t Forget Fly Control This Year
DR. TERESA L. STECKLER
SIMPSON, ILL.
The markets and social distancing have put a rather large damper on travel to farms this spring and seeing what is happening. Regardless, there are still several items cattlemen need to keep in mind this spring. One of the most important is fly (pest) control.
Flies will cost beef producers both in the cost of treatment as well as lost production. Discomfort to livestock and economic effects of heavy populations usually are apparent. Economic losses occur because feeding by horn flies, stable flies, horse flies, and other bloodsucking flies mechanically transmits several disease organisms as well as causing irritation and physiological changes that decrease weight gains. Effective control measures will allow increases in profitability in beef cattle operations.
Typical flying insects that can cause problems in Illinois include stable flies, house flies, horn flies, face flies, mosquitoes, horse flies, and deer flies. However, the two major species of flies that cause the most serious decreases in beef production and require the most control efforts are the horn fly and face fly. The horn fly alone is estimated to cause animal losses to the U.S. beef industry of between $700 million and $1 billion, while an additional $60 million is spent annually on insecticides to control infestation.
With the abundance of rain and lack of freezing weather, I have seen many farms with an abundance of hay/fecal material built up. This is the perfect breeding grounds for stable flies that prefer manure-straw mixtures, urine-soaked feed and straw, feeding waste sites, grass clipping piles, and round hay bale feeding sites. Thus, it’s important to clean up areas where there may be a build-up of hay and/or fecal materials. In contrast, horn flies must lay their eggs in undisturbed, fresh manure.
The adult horn fly, which is about one-half the size of a house fly, have brownish-gray or black bodies and are shiny, with slightly overlapping wings that are held flat over the abdomen. The thorax has two parallel stripes on the dorsal surface, just behind the head. They have piercing/ sucking mouth parts and feeds on blood and tissue fluids of cattle. They spend most of their adult life on cattle and feed 20 to 40 times a day. The crucial level of flies for losses to begin to occur is 200-250. If either young animals or cows have this many flies or more than treatment will result in increased weight gains. The face fly is about the size of a house fly. They are non-biting and prefer to be on the face and consume the secretion form the eyes and nostrils. They avoid entering dark places, such as a barn, while on the animal. They are present on cattle only about 10 percent of the time and may be found resting on fence posts, trees, bushes and other objects the other 90 percent of the time. Because they spend so little time on the animal and do not feed on blood they are much harder to control than horn flies. They are particularly important because they serve as mechanical carriers of the causative agent of pinkeye in cattle (infectious bovine keratoconjunctivitis [IBK] caused by the bacterium Moraxella bovis) and because they damage the cornea of the eye during feeding and thus allow a port of entry for the pinkeye-causing organism.
Another scourge that has reared its ugly head is the black horse fly. In addition, the heavy, persistent rains have created the perfect breeding grounds for the black horse fly. Female black horse flies attach their egg masses to plants overhanging fresh water. Larvae drop into water, feed, and then overwinter in mud for 2 winters, pupating in spring. Horse fly larvae are found near the margins of ponds, swamps and other freshwater habitats. Both males and females feed on nectar from flowers (he lacks her piercing mouthparts). Although horse flies breed near freshwater habitats, they but may travel long distances in search of blood meals. Females feed on blood and locate victims by tracking the carbon dioxide produced by respiration. Males have very short life-spans; females survive until fall. When present in numbers, these flies can be a problem for livestock due to blood loss, distress, and potential disease transmission.
Cattle can tolerate low fly populations. When fly populations reach 100 to 200 per animal it is economically advantageous to begin a control program. There are several methods of fly control, such as insecticide sprays, dusts, pour-ons, oilers, dust bags, ear tags, oral larvicides in minerals and blocks and controlled release boluses. All of these methods are effective and have a place in the control program; however, the best fly control can most likely be obtained through an integrated fly control program.
When making decisions about fly control it is important to realize that there are many effective programs. Producers should develop a program for their operations which is cost effective and most convenient.
Here are several tips to keep in mind for fly control and pesticide use: 1) Plan ahead for insecticide and ear tag purchases; fly season always comes, even if delayed by cool weather or rain; 2) Consult with your herd veterinarian regarding active ingredient(s) in products and their record of effectiveness in your area; 3) Always follow instructions, warnings, and precautions: these products can be toxic to you, your children, pets, and others working with them around the chute; and 4) Follow label withdrawal times and keep records of treatment dates, products and lot numbers. ∆
DR. TERESA L. STECKLER: Extension Specialist, Animal Systems/Beef, University of Illinois
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