A helicopter contracted by the DNREC Mosquito Control Section sprays for woodland pool larval
mosquitoes in early spring to limit emergence of adult mosquitoes later in the spring /DNREC photo

Annual Spring Campaign Targets Year’s First Mosquito Emergence from State’s Forested Wetlands

The Delaware Department of Natural Resources and Environmental Control will begin the annual spring spraying of woodland pools to control aquatic immature (larval) mosquitoes as soon as Friday, March 20 – with the spring spray campaign carrying on as late as mid-April, weather permitting.

Spraying by DNREC’s Mosquito Control Section will begin in southern Sussex County, then expand into Kent and New Castle counties over the next several weeks. Targeting early-season woodland pool larval mosquitoes limits the emergence of biting adult mosquitoes later in the spring (typically early May) coming from these habitats.

Up to 10,000 acres of wet woodlands near select populated areas can be treated annually. However, as of early March, Delaware’s recent drought conditions have resulted in below-average surface water area in the state’s forested wetlands. Additionally, the below-average winter temperature has also delayed mosquito egg hatching, with the season’s first documented mosquito larvae observed at the end of February. The Mosquito Control Section monitors these and other factors during the month of March, which in turn determines when treatments will occur for the state’s woodland pools.

All control treatments will be done via helicopter. Treatments will apply a liquid, bacteria-derived insecticide commonly known as Bti – with the timing of application ideally coinciding with a majority of mosquito eggs hatched and about halfway through their larval, aquatic life stage. As with all insecticides used by the Mosquito Control Section, Bti has been determined by the U.S. Environmental Protection Agency to pose no unreasonable risks to human health, wildlife or the environment when applied in accordance with product label instructions as required by federal law.

The spring woodland mosquito larvae spray campaign marks the annual beginning of Delaware’s mosquito control season – which in most years continues until late October.  Starting in April, mosquito control activities will expand to include larval and adult saltmarsh mosquitoes, other freshwater mosquitoes, and urban and suburban container-breeding mosquitoes to manage mosquito populations for improving the state’s quality of life and to protect public health.

Delawareans can learn locations and times for scheduled mosquito spraying activity in the state by calling toll-free 800-338-8181. Mosquito spraying announcements can also be received by email, text or voicemail by subscribing to the Mosquito Control’s Spray Zone Notification System found on the de.gov/mosquitospray webpage.

To request local mosquito control service, call one of the following Mosquito Control Section field offices:

• Glasgow Office, 302-836-2555, serving New Castle County and the northern half of Kent County, including Dover.
• Milford Office, 302-422-1512, serving the southern half of Kent County south of Dover and all of Sussex County.

For more information on DNREC’s mosquito control efforts in Delaware, visit the de.gov/mosquito webpage.

About DNREC
The Delaware Department of Natural Resources and Environmental Control protects and manages the state’s natural resources, protects public health, provides outdoor recreational opportunities, and educates Delawareans about the environment. The DNREC Division of Fish and Wildlife conserves and manages Delaware’s fish and wildlife and their habitats, and provides fishing, hunting, wildlife viewing and boating access on more than 68,000 acres of public land. For more information, visit the website and connect with @DelawareDNREC on YouTube, Facebook, Instagram, X, or LinkedIn.

Media contact: Michael Globetti, michael.globetti@delaware.gov

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