Rain may have ended the drought, but swarms of mosquitos now on the horizon Suzanne Baker, Naperville Sun, Ill. Jul. 13—Mosquito protection is a must if you're planning to spend anytime outdoors in the coming weeks, experts say. After receiving more than 5 1/2 inches of rain over the past three weeks, Naperville is seeing a bump in the blood-sucking pests, which breed in stagnant water, said Christine Schwartzhoff, budget and administration manager for the city's Department of Public Works. The city monitors the mosquito population weekly by capturing them in 12 traps to evaluate the effectiveness the city's larval control treatment and provide early warnings for when the adult populations are rising. The city also tests the mosquitoes for West Nile virus.