Fact Sheet No. 2: Fly Control
By John Maas, DVM, MS Diplomate, ACVN & ACVIM Extension Veterinarian School of Veterinary Medicine University of California-Davis and Nancy Hinkle, PHD Extension Veterinary Entomologist Department of Entomology University of California-Riverside

Description and Cause

Springtime is when you should atticipate summer and the height of fly season and begin to start planning for effective fly control. The number of new fly control products approved for use on cattle has decreased over the past several years. Part of the reason for this is the cost the pharmaceutical companies must incur in getting new drugs or dosage forms approved and part of the problem is the lack of new compounds that have been developed. The bottom line is that we must make better decisions for the use of the few products we have left.

One of the fly pests that is particularly bothersome is the Face Fly. This insect irritates the animals' eyes by using its rasplike mouth parts to cause the cattle to increase tear production and then the fly feeds on the excess tear secretions. Even more damaging is the fact that the Face Flies transmits the causative agent of Pinkeye, Moraxella bovis. This bacteria (Moraxella bovis) causes tremendous damage to the eye and significant economic losses and animal suffering. Additionally, the Pinkeye organism tends to be resistant to commonly used antibiotics and frustrates treatment attempts. Therefore, one of the main goals in Pinkeye prevention is Face Fly control.

The use of ear tags is particularly helpful for Face Fly control. However, it is recommended that ear tag application be delayed until fly populations are relatively high so that the possibility of the flies developing resistance to the insecticide contained in the ear tag is decreased. Also, it is usually recommended that the chemical class of drug be varied from year to year to decrease development of drug resistance by the flies. To control flies early in the season the use of sprays, dust bags, or backrubbers (facerubbers) is recommended. Then as the number of flies increases to high levels fresh ear tags can be applied.

Listed below are the drugs currently available for fly control in California. Some producers run cattle in neighboring states and additional products are available in those states for use on cattle. Some of the important things to remember are:

• Plan ahead for drug purchases-fly season always comes,
• Consult with your veterinarian regarding the active ingredient in these products and the history of effectiveness in your operation,
• Always follow the instructions for use on the label-these products can be potentially toxic to you, your children, and your pets, and
• Always follow label withdrawal times and keep accurate records of treatment dates.

NOTE: Active ingredients are available under a number of brand names: the ones used above are examples only and are not specific endorsements. REMEMBER TO ALWAYS READ AND FOLLOW THE LABEL.