Ask the Vet

Fly Controls for the Cow Herd


I have been using loose cattle mineral with an additive for fly control. It will only control horn flies. I want to switch to another product to help control face flies, but both the loose mineral and the supplement blocks I can find that will do this contain the active ingredient Rabon, and the label says before using Rabon with pregnant or nursing cows to consult a veterinarian. I have a small cow-calf operation, and most of our cattle are pregnant or nursing, so I'm not sure what to do. I don't use ear tags, but I do use a fly rub-scrub with strips and bullets on it. I also make direct applications on an as-needed basis. These products are permethrins.


You are correct that Rabon can help control face flies. I talked to a veterinarian at Bayer, and he is confident the product is safe when used according to the label. It has been used for over 50 years, and a lot of it has gone into pregnant cows. I do advise calling the mineral company to see what their concerns are and why this is on their label.

Another option is a newer product, ClariFly Larvicide. This is labeled as an aid for control of house flies, horn flies, face flies, and stable flies. I know it is offered in minerals and blocks, and as a premix.

Keep up the integrated pest management program -- you are on the right track.


Editor's Note:

Please contact your veterinarian with questions pertaining to the health of your herd or other animals. Every operation is unique, and the information in this column does not pertain to all situations. This is not intended as medical advice but is purely for informational purposes.

Write Dr. Ken McMillan at Ask the Vet, 2204 Lakeshore Dr., Suite 415, Birmingham, AL 35209, or email