Plymouth County Mosquito Control Project
Plymouth County Mosquito Control Project

Our Program

The Project's activities fall into six categories

1. Disease Monitoring


Gravid Trap


Light trap with CO2

2. Larval Site Identification:

Project personnel identify and catalog suspected mosquito breeding sites. Once a site has been proven to breed mosquitoes, a decision is made on how to best treat the site and it will become part of the Site Reduction Program or the Larviciding Program. The data recorded for each site include: directions to the site, dates of site inspections, results of each observation (if mosquito larvae are found – species, number/dip, and stage of development), and what action was taken (was the site treated).

3. Site Reduction:

Breeding site reduction is the most effective strategy for reducing mosquito populations. This strategy may require hand-clearing a clogged stream or even the use of heavy digging equipment to remedy the problem.

The Project does not drain wetlands and will only clear or dig on sites that have been confirmed to breed mosquitoes. Restoring the flow of a small stream or removing a blockage in a drainage ditch are examples of appropriate Project activities in the Site Reduction Program.


Winter Site Reduction Work:

Winter is a busy time for the Project doing site reduction work such as hand clearing streams and using the excavator to do ditch work.


Open Marsh Water Management (OMWM)

An important part of the breeding site reduction program is Open Marsh Water Management (OMWM). This technique is used only on salt marshes. OMWM was originally developed in New  Jersey and is considered to be an environmentally sensitive alternative to grid ditching salt marshes. OMWM holds water on the marsh, improves fish habitat and reduces evasive vegetation.  The heart of most OMWM projects is the creation of ponds on the marsh that can be used by small fish and wading birds. Ditches from the pond to areas that produce mosquitoes allow the fish to eat the mosquito larvae when they are present. OMWM is an important tool in areas where the goal is restoration as well as mosquito control.

Larviciding is the second most effective strategy for reducing mosquito populations. Most breeding sites are not appropriate for the site reduction strategy and as a result, larviciding is the Project’s primary strategy for controlling mosquito populations.

The Project uses a variety of equipment to larvicide areas that produce mosquitoes.  A Project worker using a hand-held pump can treat small sites. Sites may also be treated using a specially equipped truck. This vehicle has a hydraulic sprayer and over 300 feet of hose, which enables it to treat most large breeding sites.  However, most larviciding is done in the spring through the use of aircraft.  Using aircraft we treat approximately 10,000 acres each year. 

Bti (Bacillus thuringiensis israelensis), a biological insecticide, is the primary material used in the larviciding program. It is the only product used in our aerial program. 

4. Larviciding

5. Adulticiding

6. Public Education

While listed sixth on this page, the placement does not reflect the priority level we place on public education.  We believe that education is our top priority.  In fact, most of our website is dedicated to education.  You will find information about pesticides, repellents, mosquito life cycle, mosquito borne diseases (West Nile Virus, Eastern Equine Encephalitis, and dog heartworm), controlling mosquito breeding around the home, important state regulations, and links to mosquito information and education websites.  Additionally, we provide speakers for schools, community organizations, and civic groups.  We also have attempted to provide the schools of Plymouth County with opportunities for bringing mosquito education into their classrooms and connect it to the Massachusetts Curriculum Frameworks.


Plymouth County Mosquito Control Project works closely with the Massachusetts Department of Public Health (DPH) to monitor West Nile Virus and Eastern Equine Encephalitis Virus activity and to help determine the level of human risk. The Project runs traps for adult mosquitoes in areas we consider likely to have virus activity in mosquito populations. The mosquitoes collected are sent to the Department of Public Health (DPH) and tested for mosquito borne viruses.

Since no method of mosquito control is 100% effective, the Project sprays for adult mosquitoes.

Project personnel spray for mosquitoes, using trucks, between the hours of 2:00am and a half hour before sunrise, Monday through Friday. The Project uses ultra low volume (ULV) sprayers, which allows minimal amounts of pesticide to be used.