Heavy rains mean there are more mosquitoes around; here's how to keep them in check

EVANSVILLE− Mosquitoes have experienced a population boom thanks to a deluge of rain dumped on the Tri-State in recent weeks, supplying the nuisance insects with plenty of puddles in which to lay their eggs.

"Because of the heavy rains the populations are higher now than they were earlier," said Keith Goy, of the Vanderburgh County Health Department.

As vector control supervisor at the Vanderburgh County Health Department, it's Goy's job to keep disease-spreading insects and animals in check.

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While the biting bugs seem more of a nuisance lately than earlier this summer, for Goy they have been an ongoing concern for months.

Although the relative lack of mosquitoes for much of the summer might seem like the only good thing about the drought conditions Vanderburgh County saw in July, that is what worries Goy.

Why are mosquitoes so bad?

Dry weather keeps the nuisance insects numbers down, but it also makes it more likely that the mosquitoes that are around will spread West Nile virus, Goy said.

Goy has several reasons to be concerned. The Culex species of mosquitos that spread West Nile virus are common in the area, he said. Dry weather reduces the amount of available water sources, pushing birds and mosquitos to the same locations and making it more likely that a mosquito might bite an infected bird.

The infected mosquitos can then bite and infect people. The West Nile virus hasn't been found in Vanderburgh County this year. However, the virus often doesn't show up until late summer, Goy said, noting that it was August when infected mosquitoes were found in Vanderburgh County last year.

In 2012, another year with a hot and dry early summer with drought conditions, Indiana recorded 77 cases and eight deaths from West Nile virus.

Is there West Nile virus in Indiana?

So far this year, West Nile virus activity seems to be confined to central and northern Indiana, according to the Indiana State Department of Health, with the virus detected in mosquito samples in 13 counties.

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The state's first human West Nile infection of 2022 was reported in Lake County in late June. However, Indiana had 12 cases and one death in 2021, according to the U.S. Centers for Disease Control and Prevention(CDC).

Although mosquitoes won't bite in cool weather, Goy said those cooler temperatures have been arriving later in recent years, keeping him busy spraying and controlling for mosquitoes longer.

"I have definitely been doing it into October. It does seem like I have been doing it later in the last few years," he said.

Urban environments offer lots of places for water to collect and provide ideal places for mosquitoes to lay eggs, Goy said.

Some common mosquito species in Indiana have eggs which can stay dormant though long dry spells and then hatch after periods of flooding such as heavy summer storms, according to Purdue University's Entomology Department. But the Culex mosquitoes common in the Vanderburgh County area lay eggs that can hatch in as little as two or three days.

"The hotter it gets, the faster they go that life cycle," Goy said.

How do I keep mosquitoes away?

As little as one-quarter of an inch of water is all that is needed for mosquitoes to reproduce, according to the Indiana Vector Control Association. One important way people can reduce mosquitoes is by getting rid of those places where rainwater can gather.

Tips for eliminating mosquitoes from your property

• Check your property for breeding sites.

• Clean out leaves and debris from clogged gutters.

• Do not allow tires to accumulate outside.

• Flush out birdbaths once a week.

• Empty or turn over wading pools when not in use.

• Dispose of containers, trays, and can that can hold water.

• Cover or store canoes and boats upside down.

• Maintain backyard swimming pools and spas to discourage the development of mosquitoes. If not going to use the pool, then place a cover over the pool and pitch it in the middle so the cover will not collect leaves and rain water.

• Aerate ornamental ponds and water gardens.

This article originally appeared on Evansville Courier & Press: How can I get rid of the mosquitoes in my yard?