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Op-Ed | Should We Stop Spraying for Mosquitoes During the Pandemic?

Kyla Bennett

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Originally published and reprinted with permission from WBUR.org. 

Should We Stop Spraying for Mosquitoes During the Pandemic?


Nearly 60 years ago, Rachel Carson wrote that the “current vogue for poisons” resulted in a pesticide barrage as crude “as the cave man’s club.” Massachusetts should remember that during another high-risk year for Eastern Equine Encephalitis (EEE).

In April, Gov. Charlie Baker filed a bill to empower the state’s mosquito control board to eradicate mosquitoes “as it deems necessary.” Citing last year’s unprecedented prevalence of EEE and the fact that several localities do not have mosquito control plans, the state, under Baker’s bill, could begin widespread pesticide spraying without local input or notification. The state has sprayed once this year, about 200,000 acres in Plymouth and Bristol Counties.

The Legislature’s Joint Committee on Public Health and the Senate, in a bill passed June 11, significantly improved upon Baker’s bill. They added many more requirements to increase public knowledge of any intended mosquito mitigation, such as at least two days’ notice about the areas to be sprayed, the compounds being used and known health risks. There would also be a new task force to make recommendations next year on pest management, with some conservation organizations at the table. This bill was signed into law this summer.

Many unresolved issues remain. In the short term, we should question spraying at all during the COVID-19 crisis. In its current EEE efforts, the state uses Anvil 10+10, which has two active ingredients: sumithrin, which both suppresses the immune system and is a respiratory irritant, and PBO, a possible human carcinogen. Should we be using such compounds that may compromise someone’s respiratory system during a pandemic?

In the longer term, we want the state to shift from pesticides to prevention, especially since there is no evidence that spraying reduces human incidence of EEE. Last year, the state conducted six aerial sprayings for $5 million. The first three sprayings in August had wildly varying results, with alleged reductions in mosquitoes of 38 to 91%. The state sprayed three more times in September, despite the fact that the mosquito population had dropped to virtually zero due to cool temperatures. None of those sprayings eliminated mosquitoes carrying EEE, wasting $2.2 million of taxpayer money.

Rather than throw away money at the back end of a mosquito problem, we should increase larval control to fight both EEE and West Nile Virus. The Commonwealth itself posts on its website: “Controlling larval mosquitoes while they are still concentrated in a pool of water is easier, more efficient, and less costly environmentally than controlling dispersed adults.” And the Department of Public Health stated in June that, “Reduction of risk from EEE relies primarily on the use of personal prevention behaviors by individuals … ”

We should also be thinking about impacts on other animals critical to our agricultural economy, such as bees, which are essential pollinators of many fruit and vegetable crops. Massachusetts Department of Environmental Protection concedes that Anvil 10+10 is “toxic” to aquatic life and “highly toxic” to honey bees. Massachusetts has roughly 380 species of wild bees, many suffering population decline, partially due to pesticide use. The planet is suffering an insect apocalypse, which will affect our own ability to survive.

The Commonwealth should reconsider widespread sumithrin pesticide spraying, and concentrate on public education and supporting residents in fixing holes in screens, eliminating stagnant breeding waters in yards, and using personal repellant. We have fundamental concerns about Massachusetts’ approach to mosquito-borne disease management. There are serious scientific issues about whether ground and/or aerial spraying actually reduce disease risk, or instead poses greater risks to public health and the environment than is worthwhile.

If we can change the paradigm on mosquito control, it would indeed be in the spirit of Carson, who said in “Silent Spring” that we must assert our “right to know,” and that “we should no longer accept the counsel of those who tell us that we must fill our world with poisonous chemicals.” Because the “cure” may be worse than the problem, the question becomes whether we should use poisons at all.


Kyla Bennett is PEER’s Director of Science Policy as well as the Director of PEER’s New England field office.