Controlling Mosquitoes in Your Yard - U of I Extension

News Release

Controlling Mosquitoes in Your Yard

This article was originally published on June 11, 2009 and expired on July 15, 2009. It is provided here for archival purposes and may contain dated information.

After the excessive rain of 2008 and heavy rains this spring, mosquitoes are poised to be a real problem in 2009. To reduce mosquito problems in your yard, eliminate breeding sites. An ongoing program of eliminating these sites in your yard is actually easy and not very time consuming. However, it must be done regularly, states David Robson, one of our University of Illinois Extension horticulture educators.

Mosquito outbreaks, in which large numbers of biting mosquitoes are present for several days, are the result of lowland flooding a couple weeks previously. Eggs that are laid in these low areas can be dry for months.

Many ponds and backyard water features can be potential breeding grounds for the mosquitoes. Heavy rains that flood these areas cause the eggs to hatch, resulting in larvae that develop into adult, biting mosquitoes in about two weeks. If you have areas of your property that are flooded for at least 10 to 14 days at a time, adjusting drainage or maintaining them as permanent ponds will allow you to reduce mosquitoes from these areas.

Permanent bodies of water—such as ponds, abandoned swimming pools and garden pools—should contain top-feeding fish to eat any mosquito larvae that try to develop. Gambusia (known as mosquito fish), most bait minnows or guppies will eliminate any mosquito larvae that are present in water bodies. If the water is shallow, the fish may die from summer's heat or freezing during the winter and have to be replaced occasionally.

When selecting fish, realize that Gambusia may be difficult to find since they do not overwinter here, that guppies need water that is at least 60 degrees F. or warmer, and that goldfish may not eat

enough mosquito larvae to be effective. Minnows from a bait shop will probably be the cheapest, most available form of season-long mosquito control.

Mosquitoes can also be controlled as larvae in water with insecticides. Bacillus thuringiensis israeliensis, a bacteria that kills only the larvae of mosquitoes and closely related insects, is available in some garden centers.

Other mosquitoes will develop throughout the summer in small amounts of water that may accumulate in birdbaths, old tires, tin cans and other containers. These containers should be eliminated, pierced so that they do not hold water or emptied and dried at least once a week so that mosquitoes are not able to develop in them.

Pull date: July 15, 2009