Rains Bring Mosquito Breeding Places (375)

KNOXVILLE, Tenn. — Tennessee mosquitoes will benefit from the added breeding places created by recent heavy rains, a University of Tennessee entomologist said Monday.

“Having a very wet spring is going to make for a real good mosquito year,” said Dr. Reid R. Gerhardt, professor of entomology at the University of Tennessee-Knoxville, “although not many people agree with my idea of a good mosquito year.”

Among Tennessee’s common mosquitoes, the two most important species breed in tree holes or in discarded man-made items such as old tires, buckets or junk, Gerhardt said.

Toys left outdoors also make good mosquito nurseries and roof gutters that don’t drain dry after a rain are ideal habitat.

“People will step outside and wonder where all the mosquitoes are coming from,” Gerhardt said. “Many times the mosquitoes are just a foot or two away, in the gutters over their heads.”

Mosquitoes can transmit disease to humans, but Tennesseans are generally spared the more serious illnesses such as St. Louis or eastern encephalitis, Gerhardt said.

There was an increase last year in the number of illnesses reported due to the LaCrosse virus, which mosquitoes can carry, Gerhardt said.

“Last spring was rainy too, so we may see the same sort of increase this year,” Gerhardt said.

The best mosquito protection is a preventive cleanup of outside areas where the insects might breed, with special attention to places where rainwater collects, he said.

Insect repellants, most of which contain the ingredient Deet, also are safe and effective if used according to their directions, Gerhardt said.

Rainfall doesn’t have much impact on flea populations, although ticks may benefit indirectly, Gerhardt said.

“With plenty of rainfall, we may see an increase in vegetation — large amounts of lush plant life — and this may lead to an increase in wildlife, which means more hosts for this year’s young ticks,” he said. “This year’s young ticks will be next year’s adult ticks.”

Black flies and the tiny black gnat, or no-see-um, are biting insects common to the state’s mountainous areas.

Gerhardt said black flies are not as dependent on rainfall because they hatch in permanent streams that don’t dry up.

“Very possibly there will be more no-see-ums because many of them will breed in tree holes and marshy places that will stay wet longer than usual this year,” Gerhardt said.

Contact: Dr. Reid Gerhardt (423-974-7135)