Make inexpensive and effective traps that will attract and kill biting deer flies. Deer flies cannot be eliminated with sprays and are not attracted to most lures. My traps can catch those that want to bite me, however, which is the best that can be expected. My traps are based on information that can be obtained by performing in Internet search on "deer flies," especially at sites of University of Florida and Florida Department of Agriculture, and others, from commercially-available traps, and from my own trial and error and field testing.
University field tests suggest that bright blue is the best color for lures, so I look for inexpensive disposable blue plastic items, then slather them with Tanglefoot or its generic equivalent.
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Step 1: Personal protection
I wear one of these whenever I work outside, and they attract and hold whatever deer flies come to bite me. The high fashion added is just a bonus. Deer flies are attracted to any large, dark, warm, moving object (bonus, carbon dioxide exhalations), and the best lure I have available is myself. When I patrol the perimeter of my lot each morning and pick up trash along our nearby highway, I wear the salad bowl ($1). It is drilled in two places and attached by two plastic zip ties to a plastic hard hat that has had its crown cut out. The remains of the hard hat and its webbing hold the bowl onto my head.
When I operate motorized yard equipment, I wear the protective muffs that have a blue Solo cup attached to its frame with wire bag ties through two holes above the cup's rim.
Are they effective? All those dark dots are flies collected in just two weeks' use.
I discard the bowls and cups at the end of the fly season.
Step 2: Horse Pal trap modified
This trap is a commercial version of the Manitoba trap, which can be seen and purchased at bitingflies.com web site. It is intended for horse flies, but I bought one and found that is quite effective against deer flies. No chemicals, no poisons, but very expensive. The lure is a large, tough inflatable black ball ($50), which gets warmed by the sun. Apparently the female fly thinks she is going to get to bite a REALLY BIG horse. Once she does not find the blood meal she needs in order to lay her eggs, she escapes upward, is funneled into a clear plastic jar, where she dies from dessication (i.e., drying out with extreme prejudice). I have used this trap to try out cheaper lures of my own design for use with sticky traps.
The trap is sold with four metal legs that support it, but I wanted to hang mine up to make mowing easier. I used the metal legs as patterns to cut lengths of plastic pipe to duplicate the portion of the legs within the fabric, fastening the pipe using 45-degree elbows. I assembled a square of plastic pipe and 90-degree elbows to spread the bottom of the skirt. The lower ends of the shortened legs are fastened to the corners of the spreader using long screws and nuts.
Step 3: Horse Pal trap hanging loop
I used three lengths of plastic pipe to form a loop for hanging the trap. Exchanging plastic pipe for the trap's metal parts made it light enough to hang from a tree limb. Flies "escape" up through the wire screen funnel, cannot figure out how to get out of the jar. Very few other kinds of insects get into this trap, no beneficial insects. The dark granular band around the mouth of the upside-down plastic jar are the remains of about four weeks' catch of deer flies.
Step 4: Inexpensive lure for hanging trap
After a number of trials, I developed an inexpensive lure that worked with the Horse Pal trap, so I made several of them to use with sticky traps near my house where the flies can be a bother.
Tanglefoot is sold in a spray can, but I do not find it effective, the flies can get loose. I use a plastic hardware-store spreader to apply it from a tub. I used two screws and nuts to add the handle from a defunct disposable foam paintbrush, to help keep the stuff off my hands. University web sites say that waterless handcleaner will remove Tanglefoot, but it won't. Because paint thinner (a.k.a. mineral spirits) may have some hazards associated with it, they will not tell you that it is the only thing that will clean off Tanglefoot, and for the same reason, neither will I.
Step 5: Hanging trap lure construction
The wire is sold at home and garden centers as a "tomato cage, 33-inch" and I modify it by bending the three upright wires to form "shoulders" and to join each other, with one end bent to make a small loop that will accept a hanging string. A 33-gallon black plastic yard bag having its own plastic tie cord is modified by applying a tab of duct tape in the middle of the bag's closed edge, inside and outside, for strength. A slit is cut in the tape to allow the wire hanging loop to poke out of the bag.
Step 6: Homemade hanging sticky trap
The assembled hanging trap. The bag's plastic ties are tied together loosely to keep the bag from riding up over the bottom of the wire cage. Sun warms the black bag, and wind makes it flutter. The wire cage inside keeps the wind from thrashing the bag to shreds and keeps the bag from blowing up and getting stuck to the sticky cup. A hole is made in the cup's bottom using a hot soldering pencil, and the cup is supported by a stopper knot in the string, high enough so the cup can also be moved by the wind.
Step 7: Truck trap
One really good lure for deer flies is a warm, dark moving vehicle. I put a sticky salad bowl trap on my pickup truck, and it will just about be covered up with dead flies during a season. The bowl is connected to a plastic 90-degree elbow on top of plastic pipe. A long sheet-metal screw runs through a hole in the bowl and into the elbow, with a short, light compression spring above and below the bowl on the screw. Good movement when the truck is in motion. There is a pin through the lower end of the mounting pipe, and it fits into a groove in the top edge of a slightly larger plastic pipe.
Step 8: Truck trap in highway position
The truck trap in its lowered position, with about 4 weeks' catch stuck to it. I hope these trap ideas offer you some relief from biting flies, and GOOD HUNTING!