Justin Harbison, an assistant professor at Loyola University who jokingly refers to himself as a "sewer monster," demonstrated how mosquitoes breed in stagnant water found in sewers. During a recent inspection, he removed a sewer cover to show an area where mosquitoes had been breeding.
The sewer had already been treated with a pesticide designed to prevent mosquito larvae from developing into adults capable of biting people.
"One of the benefits of doing it that way is we're killing the mosquitoes before they become a biting problem where they start transmitting diseases," Harbison said.
Harbison said the wet conditions this summer have been ideal for creating mosquito breeding sites. He found mosquito larvae in less than an inch of water collected on a tarp, illustrating how little standing water is needed for mosquitoes to reproduce.
"Even a small amount of standing water in a house can create a problem with mosquitoes," Harbison said.
Among the mosquitoes collected by Harbison were culex mosquitoes, which are brown in color and can carry West Nile virus. Another species, the Asian tiger mosquito, is darker in color and is currently prevalent in Cook County.
George Balis of Clarke Mosquito Control said residents may encounter a wide variety of mosquito species in the region.
"We have 35 to 50 different types of mosquitoes in the Chicago area. Most feed in the evening. This one feeds in the daylight hours," Balis said.
Clarke Mosquito Control works with communities to reduce mosquito populations. While the company sprays to kill adult mosquitoes, Balis said efforts increasingly focus on controlling the insects before they reach adulthood.
Although mosquitoes cannot be eliminated entirely, Balis said a variety of effective repellents are available.
Experts say mosquitoes generally continue biting until they successfully obtain blood. They recommend wearing mosquito repellent as the best way to reduce the risk of being bitten.