Mosquito Season in Central Ohio: When It Starts, When It Ends, and What Works

Mosquito season in Central Ohio runs from May through October, and the greatest risk of West Nile virus runs from early June to mid-October, with human cases historically peaking in mid-August. Ohio State University researchers who trapped mosquitoes in Franklin County also found blood-fed, egg-bearing Culex females as late as November in two of three years, so the season can outlast the first frost. For families who use their yards from the first spring cookout to the last football Saturday, a protection plan has to cover that whole calendar.

When does mosquito season start and end in Columbus?

Mosquito season in Columbus starts in May and winds down in October, with a long tail of activity in some falls. The table places each stretch of the season next to the step that fits it.

The timing comes from the Ohio State University study of Culex mosquitoes in Franklin County, published in Parasites & Vectors, and from the Ohio Department of Health's May to October description of mosquito season.

Which mosquito spreads West Nile virus in Central Ohio?

Culex mosquitoes spread West Nile virus in Central Ohio. The Ohio State researchers report that Culex are the primary vectors of the virus across the United States, and the northern house mosquito, Culex pipiens, is one of the species routinely collected in central Ohio. These mosquitoes lay eggs in standing water, including small amounts in clogged gutters, flowerpot saucers, and buckets.

The same researchers found Culex pipiens overwintering in culverts, which sit outside any single property. What a homeowner controls is the water on their own lot, and that is where the steps below focus.

Do mosquito-repellent plants keep mosquitoes away from a yard?

Mosquito-repellent plants do not keep mosquitoes away from a yard. Iowa State University Extension concludes that growing repellent herbs around a yard does not work. Citronella grass and scented geraniums contain oils with repellent properties, but those oils are released only when the leaves are crushed. A plant sitting on a patio has no effect on the mosquitoes around it.

The plants are pleasant to grow, and they simply are not protection. Time and money are better spent on the water on your property and on a repellent you apply to skin.

What backyard steps reduce mosquitoes?

Removing standing water is the most effective step a homeowner can take, because mosquitoes need water to complete their life cycle. A weekly routine covers most of it:

1. Empty or flip anything that holds water, including plant saucers, buckets, kids' toys, grill covers, and tarps.
2. Clean gutters so they drain, and fix low spots where water pools after rain.
3. Refresh bird baths and pet water bowls weekly.
4. Screen rain barrels, and treat water you cannot drain with mosquito dunks, which contain an organic bacteria called Bti. University of Florida Extension explains how dunks and bits work.

For skin protection, ODH recommends an EPA-registered repellent used according to the label, along with light-colored clothing and less time outdoors at dusk and dawn.

What does professional mosquito control add?

Professional mosquito control adds treatment of the areas where adult mosquitoes rest, which water removal alone does not reach. D-Bug Pest Control uses targeted spray treatments around the home to reduce mosquito populations in the yard. Store-bought sprays can knock down adults briefly without addressing breeding sites, which is why professional treatment works best alongside the water steps above.

Families with pets and children often ask about product choices, and the mosquito control service page describes the options. Homeowners in Powell, Dublin, and Worthington can also review the local details on the mosquito control page for Powell.

Frequently asked questions