Prevent horse water from contamination with May flies

Asked April 12, 2016, 2:39 PM EDT

I'm a veterinarian for horses in Lancaster Co and there is a disease called Potomac Horse Fever that is spread to horses when they accidentally injest insects with a fluke that carries the disease. The most common vectors are caddis flys and Mayflies but other aquatic insects may contribute. I have horse owners that need to leave a water bucket outside in the pasture for drinking thru the day. The water is changed daily. Is there anything else the owner can do to make the water bucket less likely to be attractive to insects so they wouldn't contaminate that source. For example is one color of bucket less appealing then another? Or perhaps a wind current from a fan to keep they from landing in the water? Thank you for any suggestions

Lancaster County Pennsylvania watering

1 Response

Fish are the most common control of mayflies in natural settings. Controls for these insects that would be acceptable for feeding horses would be hard to match. Black or blue buckets would be more in line with stream colors and so you may want to try white or yellow to see if this helps reduce fly numbers. Dumping of water daily and sanitizing with a weak solution of chlorine bleach (1/4 tsp regular bleach/1gal water) may also help reduce bacteria, fly eggs & drawing flies to the bucket. It is the open water shining in sun or moon light that is drawing flies. Mayflies are considered a sign of a healthy stream and fishery.

Thank you, G.