DOVER, Del. — The Delaware Department of Natural Resources and Environmental Control will begin its annual spring campaign to control early-season mosquitoes as soon as March 20, targeting woodland pools across the state to limit the emergence of biting adult mosquitoes later in the spring.
The effort, led by DNREC’s Mosquito Control Section, will start in southern Sussex County before expanding into Kent and New Castle counties in the following weeks. The campaign typically continues through mid-April, depending on weather conditions.
The program focuses on aquatic immature, or larval, mosquitoes found in forested wetlands. DNREC says treating these areas early in the season helps reduce the number of adult mosquitoes that emerge in early May.
Each year, crews may treat up to 10,000 acres of wet woodlands near populated areas. However, DNREC says recent drought conditions have led to below-average surface water levels in forested wetlands, while colder winter temperatures have delayed mosquito egg hatching. The first larvae of the season were observed in late February.
Officials monitor environmental conditions throughout March to determine optimal treatment timing.
All applications will be conducted by helicopter using a bacteria-based insecticide known as Bti. The treatment is applied when most mosquito eggs have hatched and larvae are about halfway through their aquatic life stage. The U.S. Environmental Protection Agency has determined that Bti poses no unreasonable risk to human health, wildlife or the environment when used according to label instructions.
The spring campaign marks the start of Delaware’s mosquito control season, which typically runs through late October. Beginning in April, efforts will expand to include saltmarsh mosquitoes, other freshwater species and container-breeding mosquitoes in urban and suburban areas.
People who live there can find spray schedules by calling 800-338-8181 or by subscribing to DNREC’s Spray Zone Notification System at de.gov/mosquitospray.
Requests for mosquito control services can be made through DNREC field offices. The Glasgow office serves New Castle County and northern Kent County, while the Milford office covers southern Kent County and all of Sussex County.