Should aerial spraying be conducted in Massachusetts?

Richard PollackRobin Mozell

Aerial spraying of insecticides is a useful – though costly and controversial – method to battle mosquitoes that transmit the eastern equine encephalitis virus in the Commonwealth. This exceedingly infrequent effort is directed by state agencies, and is performed solely when and where there is a need to quickly reduce the extraordinary risk of disease over a broad area.

EEE annually infects just a handful of persons here, but the resulting disease is often devastating. One-third to one-half of EEE patients die from the disease. Survivors may suffer dire and life-long consequences, their families risk financial ruin, and taxpayers bear high costs for acute and long-term patient care. The goal of spraying is to reduce the chance of an outbreak that might cause many – perhaps many dozens – of human and horse EEE cases, not to eliminate all mosquitoes nor prevent every human case. Such interventions can dramatically reduce risk of disease.

Specially equipped airplanes efficiently treat areas where trucks cannot reach, applying less than two tablespoons of the insecticide per acre, the same amount applied in truck spraying. Locations, times and spraying methods maximize the effect on mosquitoes, but minimize effects on people, moths, bees, and other non-target animals. No species has detectably suffered measurable long-term harm. Indeed, even the targeted mosquito population’s decline is only transient, as is planned and expected.

People can lower their own infection risk by avoiding mosquito contact, covering their skin and using repellents, and can reduce mosquito problems on their properties in other ways. But mosquitoes do not respect property lines or municipal boundaries. An orchestrated area-wide public health response can be, and has proven, highly effective.

The direct and indirect costs incurred by even one EEE survivor can eclipse the total cost of a spray program. Preventing multiple cases may return even greater returns on investment, saving families and taxpayers considerable sums. Despite its value, aerial spraying has traditionally been a last choice to protect people from a serious public health threat. We do need better and more acceptable means to intervene. In the meantime, we should use this legal, useful, low-risk and cost-effective tool — but only as needed.


Laura Davis

Owner, Long Life Farm in Hopkinton; President, Massachusetts chapter of Northeast Organic Farming Association

Laura Davis
Laura Davis

Ecological farming thrives when we work with local ecosystems, rather than battling nature with chemical inputs. Because we don’t use insecticides here at Long Life Farm, insect predators like lady bugs thrive and keep common pests like aphids in check. We rely on preventative measures, rather than reactive ones, to control problem insects.

Mosquito disease management in Massachusetts has been largely reactive, relying on the broad-scale application of insecticides. In 2019 the state used airplanes to spray these insecticides over more than 2 million acres over 26 days. The product used, Anvil 10+10, contains Sumithrin, a synthetic pyrethroid, which kills more than mosquitoes, and a chemical called piperonyl-butoxide, which is considered by the US Environmental Protection Agency to be a possible human carcinogen.

These pesticides can kill dragonflies, which are one of the most effective predators of mosquitoes, along with other beneficial insects and native pollinators, and have potential human health impacts. The New York State Department of Health warns that “children and pregnant women should take care to avoid exposure when practical.”

And it’s not even clear the intent of aerial spraying is being met. The Boston Globe reported in July that half of the aerial spray applications in 2019, which in total cost Massachusetts taxpayers more than $5 million, showed no impact on the targeted mosquitoes.

We know that mosquito-borne diseases are a serious threat which will only worsen with climate destabilization and that we need an overhaul of the state mosquito control program. We are grateful to see the recent creation of a “Mosquito Control for the Twenty-First Century Task Force” for the Commonwealth. Instead of spraying, the state should focus on proactive measures, which have shown to be effective, including eliminating mosquito breeding sites, enhancing habitats for mosquito predators, using biological control of mosquito larvae, and increasing public education.

We must stop spraying toxic chemicals on our communities and invest in safer, proactive methods of mosquito control. We should not be relying on these chemicals, especially as we recover from this pandemic. We know we have better, more ecological, and effective options to control mosquitoes. Say “no “to aerial spraying of pesticides.

As told to Globe correspondent John Laidler. To suggest a topic, please contact