Expert: Large 'mosquitoes' are really disease-free crane flies
Homeowners who are concerned their backyards are being invaded by super-sized mosquitoes are really witnessing the annual emergence of harmless adult crane flies, according to the Westmoreland Conservation District’s Andrea Halfhill.
She knows about mosquitoes, since she just finished monitoring the county’s population of the winged insects this year for the presence of West Nile Virus.
The good news is only three local mosquito samples — in New Kensington, Penn Township and Latrobe — tested positive for the disease this year. That’s way down from the 98 positive samples collected in 2018. And there have been no human or avian cases of the virus reported in the county — down from one and four, respectively, last year.
Another bit of good news, Halfhill said, is that the local season for mosquitoes, which usually starts in late April, has now wound down.
“Their numbers start to drop in the fall,” she said. “I’m done (collecting samples) in mid- to late October.”
What some residents have been noticing recently and reporting to the Conservation District office actually are crane flies — similarly equipped with wings and long legs but much larger than mosquitoes, Halfhill said.
“August through October is when the adults emerge from people’s lawns,” she said of the crane flies. “It’s their season to mate. They don’t bite, sting or spread any diseases, and they only live for about 10 to 15 days.”
Local mosquitoes usually are smaller than a dime, Halfhill noted, while a crane fly can range in size from a nickel to the palm of one’s hand, with its legs fully extended.
“You may see them resting against the house,” she said. “If they get inside, they may rest on a wall.”
Halfhill explained remaining crane flies should end their life cycle over the next few weeks, as they lay eggs that will develop into larvae resembling small brown worms or grubs.
If they aren’t picked off by a predator such as a bird or skunk, the larvae will survive through the winter in turf grass, particularly in moist areas, and will feed on the grass roots, she said.
“If there’s an overpopulation, they can cause brown spots in the lawn,” she noted.
Jeff Himler is a TribLive reporter covering Greater Latrobe, Ligonier Valley, Mt. Pleasant Area and Derry Area school districts and their communities. He also reports on transportation issues. A journalist for more than three decades, he enjoys delving into local history. He can be reached at jhimler@triblive.com.
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