Why Black Fly Season Is Lasting Longer Than Usual In Upstate New York

Residents of upstate New York are no strangers to fly pest issues, especially fly pests that inflict painful bites. The northeast US sees particularly high populations of biting fly species that are most active near large and small bodies of water, such as creeks, marshes, streams, rivers, lakes and the Atlantic Ocean. These biting fly pests include black flies, stable flies, horse flies, deer flies, and greenhead flies, and they are known for feeding on the blood of humans and animals. The bites that these flies inflict often cause excessive bleeding, and they are potential carriers of disease-causing microorganisms. Biting flies have always been an issue for residents of upstate New York, but many residents and experts have noticed that the biting fly season in the state seems to be getting worse and longer each year. This year, 2019, was one of the worst years for biting fly pest issues on record in upstate New York, and this is especially true of black flies, which continued to bite residents well into August, long after black fly season normally ends in the northeast.

According to entomologist Trish Hanson, black flies usually emerge during the spring and harass residents up until the end of June or mid July, but the cold spring and early summer weather allowed the black fly population to explode in upstate New York this year. Female black fly adults must deposit their eggs in natural sources of cold water in order for larvae to survive and develop properly. By spring and early summer, natural water sources usually become too warm for larvae to survive, but this year, the unseasonably cold spring weather in upstate New York allowed black flies to continue reproducing into the summer season.

Last July, stable flies swarmed boaters and beachgoers in several upstate New York communities, particularly in the Adirondacks. Swarms of biting flies are to be expected during New York summers, but this year the swarms were so thick and prevalent that even dogs were attacked by stable flies. Stable fly season in the northeast usually lasts from July to September, but many upstate New York residents are still encountering swarms in October. Many upstate New York communities have applied for permits that allow natural water sources to be treated for black flies. These treatments have successfully decreased black fly populations in the past, but this year has proven that unseasonable weather conditions can cancel out the benefits of areawide black fly control efforts.

Are biting flies a problem in your community, or are black fly pest issues largely limited to areas located near Lake Erie?

 

 

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