Interns are helping the Hocking County Health Department monitor mosquitoes in the county.

LOGAN – Thanks to a grant from the Ohio EPA, the Hocking County Health Department has been able to hire interns to monitor mosquitoes in Hocking County for West Nile Virus, according to a release from the agency. West Nile Virus (WNV) is the leading cause of mosquito-borne disease in the continental United States. The best way to prevent WNV is to drain items that hold water so mosquitoes can’t breed and to use insect repellents.

“Early warning systems are vital so we can warn people if WNV is on the rise,” explained Environmental Director Wendy Hanna. “So far this year, none of the mosquitoes we have sent to the Ohio Department of Health (ODH) have tested positive for WNV but that doesn’t mean it’s not out there. Plus mosquitoes can transmit other diseases, such as Eastern equine encephalitis and St. Louis encephalitis so you just always need to be prepared.”

Interns set mosquito traps throughout the county, then bag and ship the mosquitoes they collect to ODH for testing and identification. If you ever see one of these traps, please leave it be.

For the first time, the health department will be testing for something nearly as important: pesticide resistance. Insects can quickly become resistant to pesticides because they have very short generations. The entire life cycle from egg to adult for a mosquito only takes eight to 10 days. This is why DDT no longer works on bedbugs. In short, if you spray an area and kill 200 out of 210 mosquitos, those last 10 mosquitos likely had genes that made them tolerant to the pesticide that was used. They then reproduce and pass the genes down to their offspring, making each subsequent generation more and more resilient. Eventually this can reach the point at which the original pesticide has lost its effectiveness altogether, no longer killing any mosquitoes.

“This testing is important so changes can be implemented in our mosquito-control program,” Hanna explained. “This is one of the reasons we do not routinely spray to kill adults because it can lead to creating resistant adults and it tends to kill beneficial insects at the same time.”

Intern Wesley Walsh explained that “pesticide testing involves using a lot of mosquitoes, more than can be trapped, so we are actually growing mosquitoes at the health department. Mosquitoes lay their eggs in small bodies of stagnant water like birdbaths, buckets or old tires. These collect and store enough rainwater for the mosquitos, and provide a habitat that is safe from predators. As such, you can expect to find upwards of hundreds, even thousands of larvae within a container that might only hold half a gallon of water or less. Even things as small as dixie cups could and often do provide wonderful habitats for mosquito larvae to grow up in.”

He went on: “Water with mosquito larvae is taken back to the health department and placed in in an enclosed container till the adults emerge. The swarm of adults are then taken out of the enclosed rearing tank and subjected to pesticide testing to see how quickly and how efficiently the pesticides used will kill them. If the pesticides are still working as expected the mosquitoes will quickly die. But if they simply are not dying, or are not dying as quickly as they should, then we know they are resistant to that specific pesticide.”

Because mosquitoes can travel one to three miles, we all need to work together and eliminate breeding habitat by turning over buckets and canoes, cleaning out bird baths and gutters, and to not litter since mosquitoes will lay their eggs in something as small as a bottle cap. And don’t forget to spray up with an EPA approved bug spray when heading outdoors!

For more information about mosquitoes or to check out where mosquitoes are being trapped, visit the health department website at

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