stable fly control

Asked June 19, 2020, 6:10 PM EDT

The stable flies this spring are out of control. I am an Ag Alumni 1976 and I have 2 horses on small acreage. My run in shed has a dirt floor which I clean every day. I also pick up all manure daily in the paddocks. I use disposable fly traps and I spray my horses daily with good quality fly spray. What can I do to help control the flies? I am at a loss because this year is outrageous. Thank you

Caroline County Maryland

3 Responses

Hello. Our Equine agent Susan Garey is out but she did email me the following response to your question

"If they are indeed stable flies these are a bit more challenging to control because they can move 10 miles or more, so while you may be doing a good job at sanitation on your property neighboring properties and conditions can impact your location. Stable flies are known as filth flies or ankle biters-they lay their eggs in spoiled or fermenting organic matter mixed with manure, soil and moisture so these conditions often occur along feed bunks, edges of feeding aprons, along stacks of hay/straw, poorly managed compost piles, winter hay feeding sites, near water sources, etc. In cattle they can cause weight loss or reduction of average daily gain of nearly half a pound per day so they absolutely can "worry" weight off of horses and or cause superficial bruising in the feet from stomping. In cattle, the economic threshold is 5 flies/leg so would expect something similar in horses in terms of when it starts causing worry weight loss. The fly sprays being topically applied to the horse only works to repel flies temporarily but doesn't necessarily kill them unless they are applied directly to the fly itself. If they are indeed stable flies, the ba style fly traps are not an effective mean of control for stable flies. The bag traps are useful in contributing to house fly control so it is important to be sure you are correctly identifying which type of fly or flies are your issue.

Other means for helping with a stable fly problem.- Spray weekly to reduce fly numbers. Knockdown sprays can provide temporary relief in facilities- Rotate chemical ingredients pyrethroids (permethrin, pyrethrin) with organophosphates(dichlorvos) throughout the season. Residual sprays can be used on buildings- again rotate ingredients. Good sanitation helps reduce localized fly development. You can try a larvicide in localized areas or a feed-through larvicide(know that there are top dress feed through options or Tribute has started making an equine feed with a feed-through larvicide already in it. Read the labeled instructions carefully. Again you need a multi-pronged approach as these options will all help but used singularly may not totally reduce the economic impact.

Finally fly boots or fly socks may be helpful if you have implemented all other means of control and your horses are still stomping or bleeding from bites on their legs. These links are examples of some of the options out there- no specific product endorsement is intended. I do not have any first hand experience using these on my own horses so I cannot comment on brands etc.

Here are some additional resources that may be of use:
and this is a webinar I participated in several years ago that found very useful on this topic:

Hopefully this is helpful to you. Please feel free to email directly if you have any follow up questions-


Thank you very much. I replied to the email before I saw to reply here. The flies are better. Apparently the chicken waste they spread up the road was the culprit.

Any tips on horseflies?

If you could, please submit a separate question on horseflies- it will help us organize the answers! Thank you!