THROUGH THE WOODS: Friendly flies?

MEMORIES GO BACK to our dairy farms where we had annoying fly problems all summer. In the early 1950s my father sprayed the porch and barns with DDT until my mother convinced him not to. She was a registered nurse who read about the latest environmental concerns and was very protective of her young family. In later years she shuddered at what children had been exposed to during those times and wondered the harm that may have been caused. We went to less poisonous sprays and repellents to protect stock and us.

Courtesy of NYS DEC

In the house we used fly swatters and those ugly sticky fly papers hung up to catch them. There were some versions of these papers and traps in the barns to reduce spraying. Some flies bite us, and flies in general carry bacteria, viruses, and diseases, including TB, salmonella, cholera, dysentery, hepatitis, meningitis. They can cause food poisoning and more. In fact, the Orkin Pest Control Company says, “Every time a fly lands, it sloughs off thousands of microbes….” It is good to keep food covered and wash hands and surfaces.

My favorite natural fly controls are birds, frogs, and reptiles which I encourage outdoors around my home, including snakes. One bird, a barn swallow, may eat more than 60 flying insects/hour. Phoebes help clean up flies on my porch. Deer are often seen running at full speed trying to evade biting deer flies. They painfully bite to cut skin, including ours, to get blood. To facilitate the blood flow, they inject an anticoagulant which contains bacteria and may cause itching or possibly a severe allergic reaction. Some flies lay eggs on or in their host which develop into larva that eat from the host. Ugh.

Fortunately, there are good aspects of these 16,000 types of flies in North America. As mentioned before, they feed numerous other forms of life. Fishermen have learned the species of flies that fish prefer and make similar artificial flies with hooks. Our New York State Department of Environmental Conservation website describes an interesting fly called a “friendly fly” (Sarcophaga aldrichi), which is a New York native species and will not hurt us. How nice.

During warm weather we have outbreaks of eastern tent caterpillars and forest tent caterpillars, and these friendly flies attack and kill cocoons of forest tent caterpillars. Adult flies start to show up a few weeks before the forest tent caterpillars start to spin a cocoon in June and early July. After feeding on the caterpillar in its cocoon the fly larva (maggot) then drops to the ground to spend the winter.

Friendly flies that you see now will affect the caterpillar populations for the next year, not this year. If you had a lot of friendly flies last year, you would probably have fewer caterpillars this year. The friendly flies are important for forest health.

The DEC also has information on types of web worms and flies at their site. Personally, I do not like flies, but I hope to someday find and thank the “friendly flies” for helping our forests. Our trees need them.

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