LEXINGTON, MA—The following information comes via the Town of Lexington website.
In an effort to help reduce the mosquito population in Lexington, the East Middlesex Mosquito Control Project will be applying a naturally occurring product called Bacillus thuringiensis var. israelensis (Bti). Bti is a biological larvicide. The trade name of the Bti formulation is Vectobac G (EPA Reg. #73049-10). The Town of Lexington does not spray (or use any type of pesticide) for adult mosquitoes but does use Bti, (which is a microbial insecticide) to control mosquito larvae.
Bti will be applied by helicopter in late April, (depending on the weather conditions and wind speed) to approximately 183 acres of land:
- Five Fields at Barberry Rd.- 21 acres
- Great Meadows- 75 acres
- Hayden Woods- 27 acres
- Tophet Swamp- 37 acres
- Upper Vine Brook- 23 acres
Bti is the only product used to control mosquito larvae in wetlands in Lexington. A granular form of Bti is applied by helicopter in April at large wetlands to control spring mosquito larvae.
Smaller areas that are not accessible by helicopter will have Bti applied by hand held sprayers to control mosquitoes. The Environmental Protection Agency classifies Bti as a relatively nontoxic pesticide. Bti is target selective to a narrow range of aquatic Diptera that affects mosquito larvae and a few closely related aquatic insects in the fly family. The order Diptera includes all true flies. All Dipteran larvae are legless. They live in aquatic (fresh water), semi-aquatic, or moist terrestrial environments and includes mosquitoes, black flies and midges. Once applied Bti stays suspended in water for 24 to 48 hours and then biodegrades as it settles to the bottom which makes it an environmentally compatible pesticide.
The EPA classifies Bti as relatively non-toxic to mammals.
During the summer months, Bacillus sphaericus and a time release methoprene product are used to control mosquito larvae and are deposited in roadside catch basins. Catch basins collect the rainwater from the roads and are covered by “sewer grates”. You may see the catch basins, or “sewer grates” marked with a dot of bright colored spray paint. The colored dot shows that a catch basin that has been treated with mosquito larvacide.
Photo Credit: Lexington Town Website.