Originally published on September 3, 2014.
If you’ve noticed an increase in the number of flies buzzing around you’re not imagining things. In fact, you could call this time of year “fly season” in southern Idaho.
Part of the reason you're noticing more flies is because there simply are more of them says Ian Robertson, a biology professor and insect ecologist at Boise State University.
Flies like warm weather. All summer they’ve been enjoying the great outdoors and breeding. There’s a new generation every couple of weeks and each is bigger than the last. Then, Robertson says the great outdoors don’t seem so great anymore.
"As fall approaches many insects, including flies, are looking for safe harbor,” Robertson says. “And one of those things is to be near dwellings, the warmth of buildings. They’re trying to find their way into cracks and window sills and into attics. So they tend to congregate in areas near our structures, which is where we often experience them.”
Robertson says there are a lot of complex factors that can affect fly numbers, like increases or decreases in their predators. But generally he says, things like a mild winter or long summer will mean more flies.
One indication this “fly season” might be particularly bad: there were no late-spring frosts so flies have had an extra month or more to do what flies do.
Find reporter Adam Cotterell on Twitter @cotterelladam
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