Mosquito season in Michigan typically begins in late April and lasts through October, with the heaviest activity hitting between June and August. For Ann Arbor homeowners, understanding this timeline is the key to staying ahead of mosquitoes before they take over your yard.
Michigan's Mosquito Season Timeline
Michigan is home to over 60 species of mosquitoes, and their activity is driven primarily by temperature and standing water. Here is what the typical season looks like across Washtenaw County and the greater Ann Arbor area:
Late April – May (Early Season): As temperatures consistently reach 50°F and above, overwintering mosquito eggs begin to hatch. The first adults emerge from stagnant water in ditches, wooded areas, and low-lying yards. You may notice a few bites during evening hours, but populations are still building. This is the ideal time to start seasonal mosquito control treatments — getting a barrier spray down before populations explode makes a significant difference.
June – July (Peak Season): This is when mosquito season in Michigan hits full intensity. Warm temperatures in the 70s and 80s, combined with Michigan's frequent summer rain, create ideal breeding conditions. A single female mosquito can lay 100–300 eggs every few days, and those eggs can hatch in as little as 48 hours when conditions are right. Standing water in gutters, birdbaths, flower pot saucers, and tire swings becomes a mosquito nursery. Ann Arbor's proximity to the Huron River and numerous creeks means there is no shortage of natural breeding habitat either.
August – September (Late Season): Populations remain high through August, especially after rain events. September brings a gradual decline as nighttime temperatures drop, but warm spells can keep mosquitoes active well into the month. Many homeowners make the mistake of stopping treatments too early — in Washtenaw County, we routinely see mosquito activity into mid-October during warmer years.
October (End of Season): The first sustained frost typically ends active mosquito season. However, eggs deposited in soil and leaf litter survive the winter and will hatch the following spring, which is why consistent seasonal treatment year after year produces the best results.
What Drives Mosquito Activity in Ann Arbor?
Three factors determine how bad mosquito season will be in any given year:
Temperature: Mosquitoes are most active between 70°F and 85°F. Below 50°F, they become sluggish or dormant. Ann Arbor's summer averages sit right in the sweet spot for peak mosquito activity.
Rainfall and Standing Water: Every rainstorm creates new breeding sites. Michigan's average of 3–4 inches of rain per month during summer provides constant opportunities for mosquitoes to reproduce. Even a bottle cap of standing water is enough for mosquitoes to lay eggs.
Humidity: Michigan's humid summers keep mosquitoes comfortable and active for longer portions of the day. On particularly humid days, you will encounter mosquitoes from dawn until well after dusk, not just during the typical twilight hours.
How Ann Arbor Homeowners Should Prepare
The most effective mosquito control strategy starts before you see the first mosquito. Here is a practical preparation checklist:
1. Eliminate Standing Water: Walk your property and dump any containers holding water. Clean gutters, fix low spots in the yard where water pools, and change birdbath water weekly. This removes breeding sites on your property.
2. Schedule Early-Season Treatment: Professional barrier spray treatments applied in late April or early May create a protective perimeter around your yard before populations build. The treatment targets resting mosquitoes on foliage, fences, and shaded areas where they hide during the day.
3. Maintain Your Yard: Keep grass trimmed and bushes pruned. Mosquitoes rest in tall grass and dense vegetation during the heat of the day. Reducing these harborage areas makes your yard less hospitable.
4. Plan for the Full Season: A seasonal plan with 7 treatments from April through October provides consistent protection. Each treatment lasts approximately 21 days, and regular reapplication prevents population rebounds between visits.
Why Timing Matters for Mosquito Control
Starting treatments early in the season disrupts the mosquito breeding cycle before populations have a chance to explode. A single untreated female mosquito in May can lead to thousands of offspring by July. By treating early and maintaining coverage throughout the season, you keep populations suppressed rather than trying to knock down an established colony — which is far more difficult and less effective.
Professional barrier treatments target adult mosquitoes where they rest and also include larvicide for standing water that cannot be drained. This two-pronged approach attacks the problem at both life stages.
Ready to Get Ahead of Mosquito Season?
Do not wait until mosquitoes are already ruining your evenings. Request a free quote today or call us at (734) 985-2899 to set up your seasonal plan. Mosquito Time serves Ann Arbor and all of Washtenaw County with professional, locally-owned mosquito control you can count on.