Friday, December 12, 2008
ConsCom has concerns about mosquito control
At its December 4 meeting, the Carlisle Conservation Commission began what may be a long discussion,about the use of town-wide mosquito control methods in Carlisle. Jeff Brem, chair of the Carlisle Board of Health, appeared before the commission with information about possible mosquito control projects.
Brem stated that the BOH was in the early stages of investigating various methods and had not yet voted to support mosquito control. He noted, however, that last August two West Nile-infected birds were found in Carlisle and that the BOH is concerned about the potential health risks associated with West Nile-carrying mosquitoes.
Brem outlined potential programs and described one that would use Bti (Bacillus thuringiensis israelensis) bacteria to kill larvae of mosquitoes and black flies. Brem presented information from the Eastern Massachusetts Mosquito Control Project (EMMCP) stating that Bti does not affect other insects, bees, fish or mammals. It has been in use for this purpose for over 15 years and it degrades, on exposure to the sun. He stated that, after talks with EMMCP officials, the most effective method to disperse Bti in a town such as Carlisle may be aerial spraying via helicopter over wetlands. He reiterated, “The objective is not to eradicate nuisance mosquitoes, but to deal with a health risk.”
ConsCom members expressed a number of concerns about mosquito control. Member Tom Brownrigg noted that killing mosquito larvae in the spring would have obvious negative effects on salamanders, toads and other animals that use the larvae as a food source. He added that West Nile-infected birds seem to be more prevalent in areas that are already using mosquito control.
ConsCom member Tricia Smith questioned the cost and efficacy of mosquito control. “How low do we need to get the mosquito density, to lower our West Nile risk? The mosquito control projects have never shown a correlation between mosquito control and decreased incidence of West Nile. I don’t think this is money well spent. If we have money to spend, we should be looking at Lyme disease where we can really have an impact on people’s health. We have so many people in town who have been affected by Lyme.”
From the audience Warren Lyman noted that the town used to belong to a mosquito control district and voted itself out after only two years. Bryan Sorrows observed that geographic areas become dependent on mosquito control. “You use mosquito control for five years and all the predators die off, then the mosquito population increases and you have to continue spraying because the predators are gone. I can think of better uses for the money.”
Although no commissioners spoke in favor of mosquito control, the commission thanked Brem for his work. Brem stated that in order to be prepared for a possible Special Town Meeting in January, the BOH would vote whether or not to propose a program for Carlisle at its December 9 meeting, if they had enough information by that time. ∆
© 2008 The