WESTFIELD, Ind. — After a hot and rainy week, local mosquito control crews are out in full force — trapping, testing and treating mosquitoes.

In both Hamilton and Marion counties, keeping mosquitoes at bay is a matter of public health, so mosquito control is done through the county health department.

“We get out early to prevent the mosquitoes from hatching, which in turn prevents disease transmission,” said Alex Davis, a vector control specialist for the Hamilton County Health Department.

In Hamilton County, more than 35 traps are set county-wide to collect mosquitoes and test for harmful diseases like West Nile virus.

“We have either known areas that hold water throughout the county, or ones that we just so happen to find while we’re out and about,” said Davis. “We stop and check them for mosquito larvae and based on what we find we apply a larvicide.”

Davis said his team will often collect samples from any body of standing water – big or small. On Thursday, crews collected a sample from a small ditch off East 191st Street near Grand Park to gauge mosquito activity. Several vials contained jumping mosquito larvae.

“We’re probably coming up on a peak as far as West Nile is concerned,” said Davis. “We start to notice an increase in that in our sample collections in about July.”

Davis say July and August are typically hotter, more humid months and that comes with more mosquitoes to carry harmful diseases.

In Marion County, experts said there’s more than 35 different species of mosquitoes in the metro area alone.

“We also do test for West Nile virus in mosquitos that we collect so that way we can quickly respond if we find West Nile in a neighborhood,” said Matt Sinsko, coordinator for Marion County’s Mosquito Control department. “That same day we can be out trying to knock down those mosquitos that may be transmitting.”

Sinsko said fogging is one of the only ways to knock down adult mosquito populations. However, he said, the most effective method is wiping out larvae populations before they hatch.

“Once mosquitoes emerge into biting flying adults, you’re really limited with what you can do,” said Sinsko. “Keeping the mosquito population low will just prevent future generations of mosquitoes throughout the year.”

Sinsko said there are roughly 50 traps placed across Marion County to catch adult mosquitoes. Using traps and water samples, Sinsko said both adult mosquitoes and larvae are brought back to the county’s mosquito lab where they can differentiate the species and determine any mosquito-borne illnesses in house. Adult mosquitoes are then used to test out the effectiveness of their treatments. 

“Mosquitoes are a big vector for certain diseases,” said Sinsko. “We’re not having a huge volume of mosquitoes right now, but there’s still a lot of mosquitoes out there right now including the type of mosquito that does transmit West Nile virus.”

Both Sinsko and Davis said their respective counties are on pace to have an average mosquito season, but one heavy rainfall could change current projections.

“Things can change quickly. All it really takes is one major rainfall to kind of turn the tables,” said Sinsko. “Rainfall and mosquitos go hand in hand. Mosquitoes have to have water in order to breed. They spend three-quarters of their life in the water.”

Sinsko said there are things Hoosiers can do to help keep mosquitoes at bay, and minimize their risk in their own neighborhood.

“Take five minutes just to walk around your house. Anything that can hold water has the potential to breed mosquitoes,” said Sinsko.

“So there’s lots of things around your house that you might not even think about: clogged gutters is a big one, things that are set out that are just collecting water. People may have set up a kiddie pool over Memorial Day Weekend and it’s still sitting there – well that’s a great place for mosquitos to start breeding.”