The Carlisle Mosquito Online

Friday, November 28, 2008

Board of Health describes mosquito control proposal

Board of Health (BOH) chair Jeff Brem announced at a public presentation on November 18 that the board has asked the Selectmen to place an Article in the Warrant for the Special Town Meeting in January related to having Carlisle join the Eastern Middlesex Mosquito Control District. The board provided information about the program and responded to audience questions.

Initial costs about $30,000

Joining the district will cost $5,000. An evaluation in the spring will cost $16,000 and involves district personnel setting mosquito traps at 16 locations, testing the mosquitoes, mapping wetland areas larger than three acres, and identifying likely candidate areas for treatment. Five hundred acres of the approximately 1,059 acres of wetlands in Carlisle would be selected for treatment. The single treatment will cost an additional $10,000 and involves Bti (Bacillus thuringiensis var. israelensis) impregnated corn pellets being applied to wetlands by ground and helicopter. Bacillus sphaericus and methoprene would be applied to catchbasins. Some strains of the Culex mosquito that can carry West Nile Virus (WNV) have a demonstrated resistance to Bti. Bacillus sphaericus is considered a particularly effective larvicide for the Culex mosquito, but not very effective for other species of mosquito. The insecticide methoprene is a growth inhibitor and prevents the larvae from maturing.

A three-year commitment to the Eastern Middlesex Mosquito Control District would be required. Brem emphasized that the initiative would target mosquito larvae in an effort to reduce the risk of WNV and Eastern Equine Encephalitis Virus (EEE). He said it would not involve spraying to control adult mosquitoes.

In addition to persons attending for general information, keepers of bees, chickens and goats were also present. Consensus was that Bti was an unlikely threat to bees but that impact on bee larvae is unknown. If attempts to control adult mosquitoes involve insecticide applications, bee populations do suffer. Brem gave assurance that ingestion of the treated pellets by animals or humans is safe. He could not give an answer when asked if the pellets could comprise genetically modified (GM) corn.

Brem started a familiar refrain: “If only one life is saved….” He was interrupted by volleys from all sides of the room: “Oh, come on!” “That kind of talk is inflammatory.” “That doesn’t advance the discussion.” “Words like that scare people.”

There has been one death reported in Massachusetts from EEE this year, likely contracted in either New Hampshire or Maine (Boston Globe, October 29). The Center for Disease Control and Prevention ( reports on both EEE and WNV. In Massachusetts there were four EEE cases confirmed in humans in 2005, five in 2006 and none in 2007. In Massachusetts there were six cases of WNV reported in humans in 2005, three in 2006, and six in 2007.

When asked if everyone on the BOH supports the proposed mosquito control program, Brem said that although the board voted to request the Warrant Article, they deferred taking a vote on whether they would support the Article at Town Meeting. They are awaiting a meeting when all five Board of Health members can be present.

The Conservation Commission is scheduled to discuss the mosquito control program with Brem at 8:45 p.m. on Thursday, December 4, in the Clark Room at Town Hall. ∆

© 2008 The Carlisle Mosquito