Fighting Flies Year-round

By The Old House Web

If you think your house is plagued with flies this year, consider this: If a pair of houseflies began mating on the first day of summer and every member of every generation of offspring survived and reproduced at the maximum rate, the resulting fly population would cover the Earth three feet deep by the first day of fall!

So says Charles Pitts, professor of entomology in Penn State's College of Agricultural Sciences. Pitts, an expert on livestock pests, says that flies seem to be getting worse in the eastern United States.

Pitts explains that the life cycle of a house fly is perfectly suited for life as a summer pest. "Their cycle is temperature-driven," he says. "The warmer it is, the shorter the time it takes for the fly to develop. In the summer, a new generation can develop every 10 days."

Each female fly lays about 300 eggs, half of which will be female. "If conditions are right, a fly population can explode very rapidly," Pitts says. Flies also can survive the winter in all stages of development. In fact, flies continue to develop during winter, although at a much slower rate.

Certain flies can become active in homes during winter, if there is a warm-temperature breeding area around the house. "This can occur if the homeowner has horses or other animals near the house," he says.

For example, the cluster fly and the face fly will seek winter shelter in houses as adults. The cluster fly is a particular nuisance in fall, when large groups of the insects seek out homes to wait out the winter. "They usually stay in the attic, but these flies will come down into the house if it gets too cold," Pitts says.

Pitts says the best way homeowners can combat flies is to make the outside of your house as inhospitable as possible.

  • Compost piles must be properly managed. "Some people throw stuff in the backyard and call it a compost pile," Pitts says. "Compost piles must be turned and tended to prevent insects from being a nuisance."
  • Pick up all pet manure and dispose of it, preferably by burying it. "Manure piles are the perfect breeding ground for flies," Pitts says.
  • Hardware stores and farm-supply stores sell traps equipped with bait to lure flies. "Don't put these near a door," Pitts warns. "I recommend placing two or three in a semi-circle at least 50 yards away from the house."
  • Don't use an outdoor fly spray. "Most of the time outdoor sprays don't do much good," Pitts says.

Once the flies are indoors, Pitts says you are left to the tried-and-true methods of elimination -- flyswatters and sticky fly strips still work as well as they did for grandma. If homeowners opt for indoor sprays, Pitts urges savvy shoppers to check the label.

"Indoor spray labels should say 'For flies and insects' and list natural pyrethrins as an ingredient. Natural pyrethrins come from the chrysanthemum plant and are safe to use indoors," Pitts says. "If the label reads 'Pyrethroid' compounds, the spray shouldn't be used inside."

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