Spraying for Mosquitos

A significant component of the Mosquito Control program's operation involves adulticiding—more commonly referred to as "spraying." Our Ultra Low Volume (ULV) Spraying Program is an effective method to control populations of adult mosquitoes.

Routine adult mosquito control

During mosquito season, the department will conduct routine ULV spraying in participating communities on a weekly basis. Each community is assigned a specific night of the week. Select your county below to see the spraying schedule for your community.

Unscheduled spraying

In addition to routine activities, we work closely with the Maryland Department of Health and local health departments in response to any concern of mosquito-borne illness. Once health officials determine a need for response, mosquito control personnel will survey the affected area to eliminate potential breeding zones and determine if there is a need for further treatment. 

If there are enough adult mosquitoes present in the area, personnel will use backpack sprayers to apply Talstar P Professional—a bifenthrin-based adulticide—onto foliage where mosquitoes rest in order to control adult mosquito populations. In certain cases, the state may determine a need for unscheduled truck-based ULV fogging in response to a public health concern. 

During a disease-related unscheduled spraying, any existing spray exemptions in the affected​ areas will be temporarily suspended. 

About the pesticides & equipment we use

Learn about the types of pesticides used in truck-mounted and aerial spraying.​​

The department is very concerned about the effects of spray activities on non-target organisms, like honeybees and bats. Therefore, the department only conducts truck mounted spraying or misting at night as bees are not active at night. The droplets in the spray have an extremely small diameter. The surface to mass ratio of these droplets is such that these droplets do not leave residue on surfaces. Like tiny parachutes, when they are pulled down by gravity, drag keeps them from falling. When bees become active the next day and crawl across surfaces, those surfaces do not have any pesticide from our spray. The droplet size averages 15 micrometers. There are 1000 micrometers in a millimeter. Spray machines are tested, by law, twice a year.

Stay informed about spraying

In the event of an unscheduled spray, the department will issue public notice. All notices will be posted on the MDA website and on the Maryland Department of Agriculture Facebook page. 

For the latest updates on spraying, contact the Mosquito Spray Alert Hotline: 410-841-5870