Early summer storms could mean mosquito problems

Subtropical Storm Alberto has departed, and the rains will eventually subside. What happens next is predictable: mosquitoes.

Every possible container around our homes, yards and neighborhoods is holding water and offering its services as a mosquito breeding site. It is up to all of us to ensure that this does not occur. Mosquitoes in their larval and pupal stages require standing water, and the most efficient, effective technique to cut down the adult mosquito population is to eliminate standing water.

But this can be trickier than it appears, and eliminating standing water will take everyone’s combined effort.

This year’s mosquito season has had a relatively slow start. Despite a warm February, a cool March slowed development, and winter was dry across middle and south Georgia, where many of Georgia’s natural mosquito habitats occur. The recent rains have made the upper portion of the state relatively wet and left water standing in low-lying areas. These temporary habitats can be very productive for mosquitoes due to the lack of fish and other aquatic predators. Localized rainfall events play a major role in most mosquito populations and their potential for disease transmission.

All mosquitoes need moisture, either standing water or boggy soil, to develop from eggs to adults. Only adult mosquitoes bite.

Georgians often remember to rinse birdbaths and dump out buckets and toys, and there are many other potential mosquito habitats that people often forget. The most common larval habitats around homes and gardens are the dishes and trays associated with potted plants. Other habitats include tarps, downspouts, underground drainage systems and boats. Basically, anything that can hold water can become a breeding ground for mosquitoes.

Used tires are a particularly problematic habitat for container-breeding mosquitoes. Residents should contact their local solid-waste departments to find out about scrap tire amnesty days or other ways to dispose of old tires.

In addition to containers, some low-lying areas will hold water, allowing flood-water species of mosquitoes to emerge. Flood-water mosquitoes commonly deposit their eggs in low-lying areas with moist soils. When these areas become flooded, the eggs hatch and a brood of mosquitoes develops. These types of mosquitoes are more common along river bottoms and across central and south Georgia. While local transmission of the Zika virus was never observed in Georgia during the recent outbreak, the risk of being exposed to the West Nile virus (WNV) continues to be a real threat. Last year the Georgia Department of Public Health recorded 64 human cases of WNV and seven deaths. The number of people exposed to the virus was surely much greater, as only 1 in 5 people exposed to the virus typically become ill. Peak transmission of WNV occurs between Aug. 15 and Sept. 15 annually, but suppressing mosquito populations now can help to prevent larger mosquito populations and the compounding effects on disease transmission.

The best way to prevent mosquito-borne disease is to avoid mosquito bites. Wearing pants and long sleeves that are loose-fitting and lightly colored minimizes our attractiveness to the host-seeking female mosquito. Only female mosquitoes bite. They need a blood meal to develop eggs. Using Environmental Protection Agency-approved insect repellents is also extremely important. When used as directed, EPA-registered repellents are proven safe and effective. Approved repellents include the long-time standard DEET, picaridin (widely used in Europe) and three materials that are classified as biopesticides by the EPA: lemon eucalyptus oil, IR3535 and 2-Undecanone.

The 2-Undecanone material is the newest EPA-approved active ingredient, composed of natural compounds from the leaves and stems of the wild tomato plant. When using any of these products, it is important to always follow the label instructions. Adults should always apply repellents to children and avoid their hands, eyes, mouth and irritated skin.

Elmer Gray is a Cooperative Extension entomologist with the University of Georgia College of Agricultural and Environmental Sciences.