Horse Pal® article reproduced from: Michigan State University's
Landscape Crop Advisory Team Alert
Volume 15, No. 16, August 25, 2000

About Crop Advisory Team Newsletters

Horsefly trap catches deer flies too!

Tom Ellis

It's always frustrating for me to tell folks that there's not much they can do when they are being harassed by certain insects, especially the blood-feeding varieties like deer flies. When you are in a situation where high densities occur, your time out-of-doors is strictly dictated and usually limited by these little demons. Probably what makes it most frustrating is their behavior of being very aggressive when it is a beautiful, hot, and sunny summer day.

Last winter I was contacted by Newman Enterprises in Omro, Wisconsin. Mr. Newman told me he is marketing a trap for horseflies (deerflies and horseflies are in the same family (Tabanidae). He calls the trap the Horse Pal and was wondering if I would put in a good word for the trap should prospective customers inquire about it. I told him that horses weren't exactly down my professional alley, but I would be interested to see how well they would do catching deer flies in backyard environments.

After I talked to him I went to their website where he had images of the trap. The Horse Pal is a very similar design that has been used by researchers to collect Tabanids for many years. They are called "Manitoba traps" and do a very good job of catching many species of Tabanids.

He sent me a trap last spring to be tested against deer flies later in the summer.

As it turns out, my oldest brother has a cottage on a lake in northern Minnesota that produces bumper crops of several species of Tabanids every July and August. His cottage is located lakeside in about a two-acre clearing, adjacent to a wet land on one side that produces the critters and bordered by woody shrubs and mixed hardwood providing ideal roosting habitat.

Since my brother was a retired duck biologist I was pretty sure I could enlist and entrust him to set up the trap, catch and count flies and keep good data records. He agreed to running the trap during a week in July and I agreed to visit him, along with my first wife, during the first week of August to collect additional data. I think the deal clincher was when I told him I would bring a jug of pickle bologna (they don't have this Michigan delicacy in Minnesota).

The Horse Pal does indeed catch deer flies. During a four-day run in July (a total of 36 hours of collecting it caught 340 Tabanids (at least 4 different species) for an average catch of 9.5 flies per hour. The best catch rate during that time was 27 flies per hour, the worst was 2.5 flies per hour (cool, cloudy day). During the seven-day collecting period in early August, when the population was waning, the trap caught an average of 3.6 flies per hour. The range of the catch rate was from 1.9 flies per hour to 6.2 flies per hour.

Since I only had one trap to work with I did not have the opportunity to set up tests that get at whether or not traps or a trap can reduce nuisance in backyard situations to tolerable levels or, given the choice will a Tabanid choose a trap over a mammal.

Newman Enterprises has a real nice website with images, testimonials, ordering information, etc. Just go to your favorite search engine and dial up

Oh yes, my brother was impressed enough to ask if he could put the trap up next summer.

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