Fly Control

By Madison Seamans MS DVM

To some people, “fly control” involves zippers. However, to those of us who love horses, or to some unenlightened, unfortunate souls who don’t love horses, but live close to someone who does, it means something else. The advent of the wildflower carpet covering the foothills every spring precedes a population of something equally abundant, if less loveable: the fly. The Bible cites Adam as the guy who named all the animals, so he is the one that came up with the name of the fly. I don’t know if he named them that because they could, (which begs the question: where did the name “bird” come from) or did he notice them first because, come to think of it, they are hard to ignore. Maybe there were more flies, or maybe God reserved editorial control for Himself, thus rejecting “@#$&! flies!” …not exactly a Biblical expression. Anyway, all God’s creatures have an important place in the ecosystem, though it is sometimes difficult to understand just what the reason is for some of them: fire ants, snakes and politicians being an integral part of that group.

No matter what you call them, they are very successful life form. They have a reputation for spreading disease, but I can’t tell you how many times a fly has landed on my freshly cut piece of watermelon. I did not throw the melon away nor did I die of some horrible enteric disease, so I think that reputation may be exaggerated. But, in reality, flies are a nuisance to man and beast alike and we spend a fair amount of money every year in an attempt to rid ourselves of these pests.

There are many varieties of flies but he most common ones associated with domestic animals during warm weather are house flies, horn flies and the big fat “horse fly”, or Tabanid, the one that looks like a toy helicopter and bites like a shotgun. The life cycle of most flies is fairly short, just a few days in most cases. Eggs are usually laid in organic matter, a polite word for poop or something dead. The larvae, little “fly students”, those disgusting things that look like mobile rice, emerge from the eggs and eat what they are laid in. Within a few days, the larvae pupate, a process where they form a cocoon, and emerge as adult flies shortly thereafter. The rapid life cycle is the reason that, no

matter what we do to kill the adults today, more keep appearing. Although most fly larvae live in dead stuff, one nasty little beast the, Habronema fly, eats living tissue, but that is the topic of another discussion.

I can’t prove it, but I suspect that Adam invented the fly swatter soon after God invented the fly, and we have been trying different methods of controlling these pests ever since. The first insecticides came into being accidentally around the turn of the nineteenth century. Chemical companies employed by the “war department” (now the United States Department of Defense) were trying to produce antipersonnel compounds—the so-called nerve gasses. Somebody noticed that the roach population in the cafeteria had declined significantly during this research, as

insects are very sensitive to nerve gasses. In fact, very small doses of these compounds with kill insects and even

intestinal parasites in domestic animals without harming the host animal. Among the first of these compounds was called a chemical alphabet abbreviated DDT. We don’t use it any more in this country because the chemical companies don’t pay our politicians enough. They do, however, pay the politicians in Mexicoand South America

very well, as DDT gives the fruits and vegetables we consume all winter that wonderfully distinctive flavor characteristic of foreign produce…but we digress.

These first insecticides, the organophosphates and chlorinated hydrocarbons were very effective and safe for everybody except with less than six legs. Then the U. S. Government, having run out of public sector employment opportunities, invented the Environmental Protection Agency. Their charter was to stifle economic development for the sake of the “environment”. (Who could be against that?) Virtually all effective insecticides were banned from the US. Now we have very few choices in insect repellants or insecticides.

Most fly repellants available at feed stores or on line at any of the horse supply companies contain pyrethrin, an extract of the chrysanthemum plant, or pyrethroid or permectin, synthetic analogues of the naturally occurring compound. The “ready to use” products have very low concentrations of the active ingredients. A careful look at the label will reveal the contents of such products. The amount of the actual repellant, typically one of the synthetic plant extracts, is commonly less than 1%. That means in a twenty dollar, sixteen ounce bottle, there’s less than .16 ounces, or fifty drops of good stuff. The rest is water, alcohol and cheap perfume.

Although all of these products are very effective if you hit the fly directly with a stream of the stuff, none of them have very good residual effects. This is especially true of the stuff that “lasts two weeks”. It’s a lot like the cell phone batteries that last 72 hours, you’re lucky to get 45 minutes out of one. So if these compounds don’t work very well, and are fairly expensive, what do we do? If you must use fly spray, buy the concentrated form, with the highest percentage of active ingredients you can find. (A 10% product is available, Permectrin II, available many places on line). To make a 1% suspension, use one part of the concentrate to nine parts water. Adding a tablespoon of bath oil and some cheap cologne will help the diluted product stick to the hair and make your neighbors think it is some expensive, designer product. The addition of a spoon of something else will wreck the math, but, come on; it’s fly spray, not calculus! Shake well before using, read all the cautionary statements on the label and throw the whole mess away because it is too dangerous to use, and may damage insects.

Other “all natural” products are available, but generally worthless. Citronella has been around for a long time,

but in carefully controlled studies, it has not been found to be an effective insect repellant. Adding garlic to the

diet of the horse may make him smell like Aunt Bertha’s lasagna, but it won’t repel flies.

Predatory insects that destroy the emerging larvae have been used with some success. However, if this is part of your fly control program, using any insecticides or repellants on the premises or horse may kill the beneficial insects. (which sorta defeats the purpose).

Despite all the chemical and biological control methods available, the three most important tools of fly control are the rake, wheel barrel, and shovel. Composting is a very effective method of killing fly larvae and facilitates control of the fly population. Pile the manure some distance from the barn. In dry seasons, wet the piles with a water sprinkler to encourage the bacterial activity that is the composting process. (On cool mornings, you will notice steam rising from the compost pile. This means it is working!) Weekly turning of the piles with a tractor scoop or high school student and aforementioned shovel will keep the bacterial culture actively chewing up the substrate that will turn in to rich mulch that will make your roses, tomatoes or strawberries very happy. Remember, no matter what you do,

your fly control method will be perfect in January. In the mean time, happy shoveling!