Fly season can be a miserable time for horses and humans. Aside from being nuisances, flying insects can be vectors (agents) for serious diseases, such as West Nile virus (WNV) and Equine Infectious Anemia (EIA).
Here are the main pests that bother horses.
This fly mills around your horse’s face to lap moisture from his eyes and mucus from his nose with its sponge-like mouthparts. It will also feed from wounds or sweet things, such as grain. The Housefly is the most common pest. Although it isn’t a biting fly, it can still spread diseases.
This biting fly resembles the housefly but has a pin-like mouthpart. It sits on your horse’s lower legs and flanks where it bites into the skin to suck blood with its tube-like beak. The stable fly is a strong flier and can travel miles.
The mosquito’s bite is itchy and unpleasant, and the mosquito can carry WNV and Eastern Equine Encephalitis (EEE.)
These strong fliers are sight hunters. It’s environmentally unsound to eradicate their breeding ground, since they choose to lay their eggs in natural marshy areas. These flies settle on their prey and then use their saw tooth to slash the skin, lapping up the resulting blood. They are vectors for the EIA virus. They don’t like shade, so horses will often head for shelter when these biting flies attack. Most fly sprays aren’t effective against horseflies and deerflies.
How can you control such a wide range of pests? Use a multi-pronged approach.
There are two efficient ways to reduce the population of stable flies and houseflies: feed-through products and parasitic wasps. Both stop flies at the larval stage, before they become adults.
Feed-through fly control is a supplement that you mix with grain. It has an insect growth regulator (IGR) that travels within the intestinal tract and is passed in the manure without being absorbed by the horse. The IGR in the manure prevents housefly and stable fly larvae from developing an exoskeleton. For the product to work effectively, all horses on the property have to be on it. Properly dispose of untreated horse manure from visiting horses.
Another option is to use parasitic wasps, tiny insects that are harmless to humans and horses, but prey on the types of flies that breed in manure and rotting vegetation. The female wasp drills a hole through the fly pupa, lays her egg, and then the dead pupa becomes a food source for the developing wasp.
Release wasps when the weather is at least 45 degrees for three consecutive days, which is just before flies start breeding. Use the proper dosage for your situation (suppliers have usage calculators on their websites), apply them monthly, and place them where flies breed, such as in urine and manure spots, around water troughs, manure piles and where decomposing organic material exists. Parasitic wasps also have no resistance to insecticides, so you can’t use overhead sprays. You can use fly spray, but make sure to you spray your horse away from any areas treated with wasps.
Fly season doesn’t have to be endured; with a little forward-thinking, you can control flies and have a pleasant summer.
Tap here for a chart of fly control methods >>
Fly Control Resources >>
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Great advice. Having a couple of chickens around the barn is also a great way to clean up spilled feed.
I wonder about the IGR in the manure though. I use the manure as fertilizer. Will it affect my beneficial plant insects?
Wow. Good tips. If only the owner of my boarding stable cared enough to do anything about it.....maybe someday.......