A common house fly. Courtesy County News Center

It’s been a long, hot summer. From June through August, the National Oceanic and Atmospheric Administration reports it’s a fraction hotter than the dust bowl summer of 1936.

But that’s not bad news — if you’re a fly.

While we humans worry about wildfires and drought, the common house fly not only survives but thrives in hot weather. So said a researcher’s study published in Scientific American.

They found that in a hotter world “you’d have a larger fly population which is able to hang around for a longer period of time.”

The National Academy of Sciences has published research that indicates that other insects, like butterflies and bees, unlike flies. have been adversely affected by the warming climate.

Which might explain why this summer when eating outside more flies seem to be buzzing around your food. It hasn’t escaped the attention of a veteran waitress at a cafe near downtown San Diego. She said “trying to get the food on the table and keep the flies away is a problem.”

The restaurant has an A card from the county health department so it’s not dirty,
it’s just, she says, that “they have increased big time.”

So much so that the Ace Hardware store in Hillcrest is out of its stock of fly swatters. A clerk answering the phone at the store says it has been out of the swatters for several weeks now. He speculated it’s because the flies “are everywhere.”

Tracking fly complaints is what the county’s Department of Environmental Health Vector Control Program does. County spokeswoman Donna Durckel checked the history of non-poultry fly complaints in the county and found that there have been just under 300 complaints over the last five years.

Chris Conlan, known at the county as its “bug and critter guy,” says the numbers really don’t indicate much other than “a lot of people aren’t aware of what we do.” The data shows that outside of the city of San Diego, the largest numbers of complaints are from El Cajon, Spring Valley, Lakeside and Fallbrook.

Conlan, supervising vector ecologist for the county, says that the growth rate in the number of flies is affected by temperature and that “heat can exacerbate it.” He explains that during a typical summer, a fly reaches maturity in 10 to 12 days. But when temperatures climb, the growth rate accelerates and full maturity is reached in under seven days.

He points out that flies love moist decaying matter. Dog or cat poop in the sun is only of brief interest as it dries out, he said. Garbage cans with spoiled food or a dead animal will keep the flies around; otherwise, they are transitory, and it’s often “difficult to figure out where they are coming from,” says the ecologist.

What can you do besides arming yourself with a fly swatter? These are the recommendations from San Diego County’s Environmental Health and Quality website:

  • Use garbage cans that have tight fitting lids and do not have holes
  • Wash the inside of garbage cans often
  • Throw away food and leftovers in plastic trash bags and tie them right away
  • Place grass clippings in plastic bags and tie up bags
  • Pick up animal droppings as soon as you can and tie in a plastic bag
  • Remove fallen fruit and vegetables right away

JW August is a San Diego-based broadcast and digital journalist.

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