Plymouth County Mosquito Control Project
Plymouth County Mosquito Control Project

Pesticide Information

Below you will find descriptions of the pesticides most commonly used at Plymouth County Mosquito Control Project.  We have also included  their labels and safety data sheets.


Bacillus thuringiensis israelensis (Bti) is a soil bacterium that was discovered in Israel in 1977.  Bti has been used in mosquito and blackfly control for many years. The insecticide is created when the bacterium Bti is placed in unfavorable conditions it hardens and forms spores.  Within these spores is a parasporal body comprised of proteins.  These proteins have insecticidal properties.  When a mosquito larva ingests the Bti portions of the mosquito's gut rupture, killing the larva.  When we use Bti to control mosquitoes the bacteria is dead and no live organisms are released into the environment.

Bti is specific to mosquitoes, blackflies and midges. It breaks down quickly in the environment and is essentially non toxic to other insects, humans and other mammals.

Plymouth County Mosquito Control Project uses Bti as our primary larvicide.

Methoprene is a growth regulator and prevents the immature insect from developing normally.  The insecticide mimics juvenile hormone.  Juvenile hormone has several functions within an insect.  If the the hormone is present when the larva molts the insect will remain a larva.  If the hormone is absent the larva will become a pupa and begin to develop into an adult insect.  Since methoprene mimics juvenile hormone the larva is prevented from developing into an adult. 

Plymouth County Mosquito Control uses methoprene mainly in two situations.  We use the insecticide in catch basins to control the mosquitoes responsible for transmission of West Nile Virus.  We also use the chemical in areas that will produce mosquitoes repeatedly throughout the summer such as in salt marshes.

Altosid Label and Safety Data Sheet


Duet - Duel Action Adulticide is a synergized synthetic pyrethroid consisting of 1% Prallethrin (ETOC), 5% d-Phenothrin (Sumethrin), 5% Piperonyl Butoxide, and 89% other ingredients such as mineral oil.  Duet's EPA Reg. No. is 1021-1795-8329.  The product breaks down very quickly when exposed to sunlight.  Therefore residue on plants and other treated surfaces should be short lived.  Plymouth County Mosquito Control applies this chemical using truck mounted ULV (ultra low volume) sprayers.  The Project uses an application rate of 0.62 fl oz per acre.

Initial field trial and cage trial observations have shown that DUET causes “benign agitation” – a non-biting excitation of mosquitoes.  Benign agitation has the potential to draw mosquitoes from a resting state – possibly including mosquitoes never before factored into efficacy calculations -- into on-the-wing activity. When mosquitoes are flying rather than resting, more of the spray comes in contact to kill them.

DUET has the same environmental profile as Anvil, which is widely regarded as having minimal environmental impact.  No special steps need to be taken by residents in areas where DUET is applied, and you can go outside immediately after DUET has been sprayed.  Very little DUET is required for superior control -- one to just over three tablespoons of formulated product treats an area the size of a football field.

A distinct advantage for late-season applications, DUET also demonstrates an ability maintain its efficacy even in colder weather.  This gives improved coverage for early- and late-season applications – prime time for combating West Nile Virus.

Duet Label and Safety Data Sheet 

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VectoLex WSP is a water-soluble pouch containing VectoLex CG.  The formulation is ideal for treatment of "closed" habitats such as catch basins/storm drains and other small breeding sites.  The pouch is placed directly into the breeding site and is very useful for control of West Nile Virus (WNV) vectors in urban and suburban areas.  Under typical environmental conditions, VectoLex WSP provides up to 4 weeks of control in catch basins/storm drains.

VectoLex WSP Label and Safety Data Sheet

VectoBac 12AS Label and Safety Data Sheet.