Face Fly Control

— Written By and last updated by Annie Thompson
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Cattle Fly Control | North Carolina Cooperative Extension

Face Fly Control

Greg Traywick, Cleveland County Extension Director

March, 2021

Wet spring weather usually means greater numbers of face flies, a common pest of pastured cattle in western North Carolina. By developing an effective face fly control program for your beef herd, you can significantly improve animal performance and welfare (comfort), and increase profits.

Female face flies feed on the eyes and muzzle of cattle, moving frequently from one animal to another. Using their stomatal teeth, these parasites rasp away at the hosts’ eyes and mucous membranes, garnering nutrition from tears and mucous. This feeding activity is particularly irritating and stressful, causing cattle expend energy throwing their heads and flicking their tails. Grazing is disrupting when animals bunch together with their heads inwards to avoid attacking flies. These behavioral and physiological responses to irritation results in production losses, including reduced fertility, growth, and lactation. Furthermore, flies scratch the cow’s eyes and mucous membranes while feeding, creating sites for disease organisms to invade the damaged tissue. Female face flies are known to transmit pinkeye, brucellosis, and IBR. Fortunately, vaccines are available to help prevent these debilitating diseases. Contact your veterinarian regarding their efficacy and their use.

Controlling face flies can be difficult, and none of the presently available control strategies are completely effective. If face fly populations are high, more than one method of treatment may be required in order to achieve acceptable control.

Dust bags are commercially available and easy to use. Most are sold in kits containing the dust bag, rope for hanging, and two packages of insecticide dust. Refill kits are also available. Dust bags will last for several seasons…especially if hung properly and then taken down and stored in a dry, protected place when fly season ends. Dust bags will only provide good face fly control if they are placed where cattle are forced to use them every day. The most effective way to assure this is to isolate the water source and force the cattle to pass under the dust bags to drink. If you water your cattle out of tanks, it is very convenient to set up forced-use dust bags. The tank can be enclosed with a strong wooden fence, allowing at least 12 feet of room around the tank so animals can drink comfortably. Often, dust bags are hung too high. Hang them low, about knee high, so that the cattle have to pick them up with their heads when they pass by. They must be hung low to give effective face fly control on small calves as well as on the adult animals.

Ear tags impregnated with insecticide can also provide relief, provided they are used correctly and steps are taken to prevent buildup of resistance in the fly populations to the insecticide in the tags. Otherwise, they’ll work well in your herd for only a year or two. New insecticide formulations aren’t developed very often, so it is important to slow the buildup of resistance by paying attention to detail. To avoid this problem, be sure to read and follow label instructions. Be sure to apply two tags per animal if directed (one in each ear), and be sure to tag the calves, too. Don’t apply fly tags too early in the spring; wait until you see evidence of face fly activity (flies present, cattle expressing annoyance and defensive behaviors, etc.)  Most crucial to preventing a pesticide-resistant fly population… be sure to remove tags at the end of the season (usually first frost).

Feed-through insecticides contained in feed additives or free-choice minerals can also reduce fly populations, especially when used in area-wide control programs. These products contain a larvicide or insect growth regulator that passes through the digestive tract and into fresh manure, where female flies lay their eggs. These chemicals keep new generations of flies from developing, but have no direct effect on the adult face flies infesting your cattle. Immigration of flies from neighboring herds can overwhelm control efforts… so if you’re using feed-through products, encourage your neighbors to use them too. These feed-through products are designed to be fed 30 days prior to the emergence of flies, so you will need to start using them in early spring.

Pour-on & spray insecticides can also be effective, especially when combined with other control strategies. If pour-on fly treatments are administered at the same time you put the fly tags in, you get a fast jump on the fly population. You can also use this trip through the chute as an opportunity to deworm your cattle. Whole-animal sprays are cost-effective and provide quick temporary relief, but need to be re-applied on a regular basis, typically every 10-14 days.

In summary, a successful face fly control program requires advance planning, close observation, determining the best control methods that you can implement on your farm, and following label directions on the products you use to get optimum control and decrease the chance of resistance. The payoff is a happier, healthier, and more productive herd.