Summer Fly Control

With summer conditions come worry and loss associated with fly infestations of cattle. Economic losses occur because of the agitation the flies may cause, because they suck blood from the animals and they spread cattle diseases such as pinkeye. Effective control measures will allow increases in profitability in beef cattle operations.

The 5 flies that affect cattle the most are horn flies, face flies, heel flies, deer flies and horse flies. Let's try and break these down to some manageable control pieces.

Horn flies are the flies we see on the backs, side and poll areas. They are blood sucking flies that feed 20 to 40 times per day. The critical level for treating these flies is around 200 to 250 flies per animal. Calf weaning weights show 20-27 pound increase per calf when effective horn fly control is implemented.

In recent years, horn flies, on some farms, have developed a resistance to pyrethroid based fly control methods and this can create a need for alternative methods of control. This resistance has developed when flies were exposed to insecticides too early, at too low a dose or for too many years in a row. Plans are available at the extension office for a "walk-thru horn fly trap," which is a non-insecticide way of attacking horn fly control.

The second major fly is the face fly. This fly is larger and more robust than the horn fly and spends only periodic feeding times on the cattle during the day. As the name implies, they prefer the face and consume the secretions from the eyes and nostrils. Control is of importance because they transmit the pinkeye bacteria organism from one animal to another and because they damage the cornea of the eye during feeding and thus allow a port of entry for the pinkeye-causing organism.

Heel flies lay the eggs that produce cattle grubs so their damage comes later. However, heel flies cause cattle to be nervous and spend less time grazing when the flies lay their eggs on the lower legs of cattle in late summer.

Deer flies are biting flies, but they don't feed as regularly on one animal like horn flies. Deer flies are more nuisance flies disrupt the grazing patterns of cattle and cause them to spend energy to get away from the pest. They are hard to control in pasture situations.

A number of methods are available to control flies on cattle. Table 1, lists some of the products and application options. Please note this is not a complete list. Check with your ag supplier and read the label. Control products fall into five basic categories, pyrethroids, organophosphates, combinations, oral larvacides and avermectins.

Ear tags are on of the most convenient methods for fly control. They give good control of horn and face flies. However, fly tag use has resulted in the most resistance. Ear tags should not be applied until June and must be removed 4-5 months later. Applying one or two tags per animal as the directions indicate. This puts the tags in when it will kill the most flies and cause the least amount of resistance. Too often we see cows with fly tags in the winter. This can lead to resistance to the insecticide by the fly. New second generation pyrethroids, organophosphates and combinations of the two offer some good options for fly tag use against resistant flies.

Sprays, dust bags and rubbers are good ways to apply insecticides, but they are less convenient. They provide good control of horn flies, but are slightly less effective for face flies. Most of these products are organophosphates, although some are pyrethroids. Dust bags and rubbers (oilers) must be located where cattle will be forced to use them. The best locations are near mineral feeders or water troughs, but they should not be placed over them because of accidental poisoning could occur. Dust bags and cattle rubs must be recharged regularly so there is a constant supply of insecticide.

Pour-ons are easy to apply, but their duration of control is limited (usually 28 days.) In addition, they only control horn flies. Most of the pour-on products are organophosphates or avermectins. For these products, the fly control is usually an added benefit of using them for deworming or lice control. The marketing of generic products has reduced the cost somewhat.

Oral larvacides are of limited use in pasture situations because flies can travel a great distance to find cattle. Entomologists have documented that horn flies regularly travel up to 3 miles to find cattle. So even though the oral larvacide is reducing fly populations on your farm, flies could be coming from other locations. Oral larvacides were designed for feedlot or drylot situations and provide a good option in those environments.

· Young cattle should receive more attention. They are more susceptible to pink eye and rate of gain affects. · Use fly control products only during the peak fly control season (June-October) · Use a combination of methods (such as tags and occasional sprays, but use the same product during the same years. · Rotate types of insecticides yearly. · Dustbags, oilers, face mops and other "self medicators" can be very effective because they provide for a long term high concentration of insecticides on cattle (location is important to insure constant use.) · The use of two fly tags (one in each ear) extends control by only 10-14 days in most areas. · Develop a program which works under your management, is cost effective and most efficient.

Ask for MU Guides G7012 Making and Using a Cattle Backrubber G1195 Walk-Through Trap to Control Horn Flies on Cattle


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	Matt Herring - Agronomy/Natural Resources Ken Bolte - Farm Management/Livestock Franklin County University Extension Center Last revised: 11/28/05	Go to Franklin County University Extension Center page

Category of insecticide	How applied	Common names or brands
Pyrethroids	Ear tag, spray, pour-on	1st generation - Actoban, Ectrin, Gard Star, Rabon, Durasect, Brute; 2nd generation - Super Deckem, Cutter Gold, Saber, Cylence
Organophosphates	Dusts, spray, ear tag, pour on	Diazinon, Chorpyrifos, Malathion, Fenthion, Co-Ral, Commando, Patriot, x-Terminator, Optimizer, Spot-on, Lysoff and many others
Combination - pyrethroids and organophosphates	Ear tags	Double barrel, Max-Con
Oral larvacide	Bolus or feed additive	Rabon oral, Vigilante bolus
Avermectin	Pour on	Ivomec pour-on, Ivomec Eprinex, Dectomax, Cydectin