House flies hatch early this summer, bug people eating outdoors

Grab your fly swatters, Sacramento – our winged friends are here earlier than usual, and they’re not leaving anytime soon.

The common fly is a familiar nuisance in Sacramento as it visits a hamburger bun or hovers around a freshly poured drink on a hot night, but it doesn’t typically start buzzing until mid- to late-summer. Because of this year’s warm winter, however, female flies began laying eggs in February rather than March, resulting in a bigger litter in June, said Lynn Kimsey, director of the Bohart Museum of Entomology at UC Davis.

“The reproductive cycle of insects is entirely temperature dependent,” she said. “The warmer it is, the faster it goes.”

The Sacramento Valley has long been considered fertile ground for house flies, which thrive on garbage, the area’s especially large agricultural scraps, feces and other organic material.

Sacramento could even be considered “the fly capital of the world,” joked Pat Copps, Pacific Division technical services manager for pest control company Orkin. “At the beginning of summer, when the weather is 85 to 95 degrees, that’s when it happens,” he said.

Warm conditions can shorten a fly’s pupal stage from up to five months to as short as three to six days.

Drier conditions also mean flies’ mortality rates are lower, with many more surviving to breed, Kimsey said. Many house fly maggots are killed by low temperatures or mold during wet, cold winters.

“I joke about there being five seasons in the Sacramento Valley – winter, spring, summer, fly and fall,” she said. “But it’s just pretty much fly this year.”

The insects can be more than an annoyance – they’re known to carry more than 100 human pathogens, including the bacterias that cause typhoid, cholera, salmonella and dysentery.

Janelle Gollihur and her friends lamented the fly boom during a lunch break last week on the large front porch of the LowBrau Bierhall, a 20th Street eatery.

“It’s all the time, really,” she said of the flies. “We’re just waving in each other’s faces all the time and sometimes you knock over a drink ... We shoo them away, and they usually get the hint.”

This story was originally published July 10, 2015 at 10:48 AM with the headline "House flies hatch early this summer, bug people eating outdoors."