Control Measures

Quick Contact Numbers

Division Number
General Services 410-535-1600, ext. 2327
Mosquito Control  410-535-6924
Public Works Main Line 410-535-2204 or 410-535-2205

Mosquito Control Measures

Our program employs Integrated Mosquito Management, using a combination of physical, biological, and chemical controls, to reduce the mosquito population.

Physical Controls

Homeowners can play an important role in the reduction of tiger mosquitoes by eliminating their breeding sites. Any container holding water for five days or more is a potential breeding site. Therefore, children's toys, wading pools, bird baths, flowerpot saucers, tarps, old tires, etc. must be routinely emptied. It takes only one teaspoon of standing water to breed mosquitoes.

Biological Controls

Biological methods for larvae control are extremely cost effective as mosquito larvae are contained in a much smaller area compared to that of adult mosquitoes and are more effective in reducing the population. Gambusia (mosquito fish) are available to all communities who have suitable habitat, i.e., stormwater management ponds, or any permanent water impoundments. (See Mosquito Fish page)

Chemical Controls

Communities can request our services for mosquito control. We sample the adult mosquito population in the area on a weekly basis to determine the size and species composition of the mosquitoes. Spraying is scheduled if the mosquito population meets or exceeds a predetermined threshold. A threshold is determined when the population is high enough to cause an impact on most people's quality of life. In Calvert County, we use two methods to determine thresholds. First, landing rate counts of three mosquitoes landing in two minutes, and second, New Jersey light traps to collect mosquitoes with a threshold of 12 female mosquitoes per night.

The spraying schedule is determined by mosquito population threshold count and weather conditions. Mosquito counts can vary widely on a weekly basis due to weather. Scheduled spraying is sometimes cancelled because of inclement weather or poor air quality. We do not make up cancelled dates unless there is an extreme need that would warrant such actions.

Protecting the Environment

The insecticide used in the adult mosquito spraying is a synthetic Pryethroid called Permethrin. This insecticide has a low toxicity to people and other mammals and breaks down quickly in the environment. As it is toxic to fish, we are required to follow the guidelines set forth by the Environmental Protection Agency; and as it is toxic to bees, applications are made in the morning or evening after most bees have stopped foraging for the day.

The majority of our time is spent controlling mosquitoes before they become biting adults. Mosquito larva is usually more concentrated in smaller areas; therefore easier to control. We use mosquito fish as a biological control and we directly target the mosquito larva with larvicidal products. Truck spraying to control adult mosquitoes is our last line of defense.

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