Mosquito Season in Chicago — When It Starts and How to Protect Your Home

Mosquito activity in Chicago begins in late May once nighttime temperatures consistently exceed 50°F. Populations grow rapidly through June and peak in July and August, when heat and humidity create ideal breeding conditions across the city's parks, alleys, and standing water sources.

By late September mosquito activity slows, and by mid-October most adult populations have died off — but eggs overwinter and hatch the following spring.

Our mosquito program combines targeted barrier sprays on shrubs, fence lines, and shaded resting areas with larvicide treatment of standing water sources. Treatments last about 21 days, so we typically schedule monthly visits through peak season.

We also identify breeding sites you may not have noticed — clogged gutters, plant saucers, kiddie pools, and birdbaths — and recommend simple fixes to prevent re-infestation.