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Horn flies take up residence

From the Farm

September 7, 2012
By Kerry Hoffman , The Journal

Can this year get any more awkward?

If the waterless summer and fall wasn't hard enough on our cows, now we have to add in the pesky little creature known as a horn fly.

The horn fly, also known as Haematobia irritans, is wreaking havoc on our cows especially the ones that have the privilege of spending time out on the pasture.

Article Photos

Kerry Hoffman

Just look at the scientific name of this pesky fly. I am not a scientist by any means, but the first word haemotobia looks like it refers to blood. The second word irritans eerily resembles irritating.

That's exactly what these flies are: irritating blood suckers.

After a bit of research, so I would know how to properly dispel these creatures, I have come up with a solution to the problem.

Total eradication. (Although, I don't think this is at all possible.)

Each horn fly chooses one particular cow with which to spend its entire life. Not that their lives are all that special, they only live two weeks, but their reproduction is rivaled only by rabbits. Having such a short life is a good thing as an infestation starts to affect the growth and production of cattle.

After a fly chooses its desirable host cow, it spends day and night biting the cows and sucking their blood.

It's all very disturbing in my opinion. What a worthless life. Why do we need such creatures?

Each fly will leave the cow for a few short hours to go lay its eggs in fresh, moist manure and then it returns to the exact same cow. For this reason, I have surmised that all horn flies are female. I don't think a male fly could leave his host, go party in a cow pie and then find the host again. And get this, these pointless flies will travel 10 miles to find a host. (Purportedly, some horn flies will lay eggs in manure before the cow has even finished her job. Now that is rude.)

Depending on how warm the fly wants to be, it will move around on the cow to meet her requirements to maintain her body temperature. Apparently the warmest part of the cow is on its shoulders.

The horn fly will bite the cows mostly along the shoulders and on her belly.

That has to hurt. A fly biting my ankles hurts; I can't imagine what a fly biting my belly would feel like. I bet it would hurt, because there seems to be a few extra layers of stuff on my belly, and it would just take more effort on the part of the fly. Not that I would feel sorry for it.

When the cow is continually bitten, she starts to look like a freshly plucked chicken with all those little bumps on her skin. Each of these bumps forms a scab that makes the cow's hair puff out. It's also reminds me a bit of how it resembles the look of chicken pox.

Anyway, we all know that the udder of a milking cow is on her belly. Where these flies like to bite and suck blood is awfully close to the teats on the udder.

In the milking parlor, I have observed these flies landing on the teat end and drinking the milk. Well, I think they are drinking the warm milk. I really have no idea what else they would be doing there. During the fall season, it is my goal to post dip the teats with iodine as soon as the milking unit comes off, which prevents the flies from setting up residence on the teat end for any period of time.

I think these darn flies are spreaders of mastitis-causing germs. I mean, if a fly is spending time spreading her eggs around in a fresh cow pie, she can't be the cleanest pest in the quarter section. I bet that fly doesn't spray her feet off before she comes back to the cow. (We spray our boots whenever we enter the parlor after walking in manure.)

Horn flies are harder to catch and kill, compared to a house fly. I have slapped the backs of the cows covered with horn flies and not killed one. I have picked the head off one, so I could get a better look at its body and wing shape. That way I would be better able to identify it when I did my Internet search. Little did I know that head would have been a dead give-away during identification. I tossed it aside.

I will admit, after seeing the damage these flies do to our cows, I took a little bit of pleasure pulling the head off and tossing it like a used Kleenex.

I am glad to report there are things we can to do stop horn flies from making our cows miserable. (Remember, miserable cows don't make milk and they don't have any way to scratch an itch.)

I purchased what we refer to as a pour-on insecticide. Each cow will receive one tiny 12 milliliter squirt of insecticide across her back. That's about two teaspoons per cow.

A natural way to reduce horn fly population is the dung beetle. He, or she, will feast on the eggs of the fly, but it would take many, many dung beetles to make a dent in our population of horn flies.

We applied the insecticide on Tuesday morning; by Wednesday morning there was a noticeable reduction in the horn fly population living on our cows.

I have temporarily banished the horn fly from our cows.

For questions, or comments, e-mail me at



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