EEE Information

EEE Information
Mosquito Sample Results and Risk Levels
Preventing Mosquito Bites brochure
MA Department of Public Health and the MA Department of Agricultural Resources Press release 9-10-2019

How is aerial spraying conducted?

Aerial spraying is conducted by aircraft, beginning in the early evening and continuing up until 4:30am the next morning, in areas of concern.  Mosquito control professionals apply approved pesticides as an ultra low volume (ULV) spray. ULV sprayers dispense very fine aerosol droplets that stay aloft and kill adult mosquitoes on contact.  The spray area is designed to target areas that EEE activity originates from.

What pesticide product would be used in the aerial spraying?
The pesticide used is called Anvil 10+10, a product extensively tested and used in both ground-level and aerial spraying in the U.S. to control mosquitoes. Anvil 10+10 contains two ingredients: Sumithrin and Piperonyl butoxide.  Sumithrin is an ingredient similar to the natural components of the chrysanthemum flower which is also found in other pesticide products used indoors, in pet shampoos, and tick control treatments. Sumithrin is rapidly inactivated and decomposes with exposure to light and air, with a half-life of less than one day in the air and on plants. In soil, it degrades rapidly. Sumithrin has proven to be extremely effective in killing mosquitoes worldwide for over 20 years. Piperonyl butoxide (PBO) serves to increase the ability of Sumithrin to kill mosquitoes. The product is registered by EPA and in Massachusetts for this use.  It was used in previous aerial applications for mosquito control (2006, 2010, 2012). It is also used by some of the Mosquito Control Projects for ground applications.


Are there any health impacts associated with exposure to Anvil 10+10?
There are no health risks expected during or after spraying. There is no evidence that aerial spraying of Anvil 10+10 will exacerbate certain health conditions, such as asthma or chemical sensitivity.


Are there precautions I should take if aerial spraying will occur in my area?
No special precautions are recommended.  Aerial spraying is conducted at night and the active ingredients of the pesticide product used for aerial application for mosquito control generally break down quickly and leave no residue.


Although aerial spraying is considered necessary to reduce human risk, it will not eliminate risk. It is critical that residents protect themselves from mosquito bites by staying indoors during peak mosquito hours between dusk and dawn, applying insect repellent when outdoors, draining standing water where mosquitoes breed, and repairing screens on doors and windows.

Even if no precautions are required, are there extra steps people can choose to take if they are still concerned?
Although not necessary, steps that can be followed in areas where aerial spraying is scheduled to take place include:

  • Close windows and turn off fans in spray areas. Shut off air conditioners unless they have a setting for recirculating indoor air. In very hot weather, you can open the windows or turn fans and air conditioners back on soon after the aerial spraying is completed.
  • Keep pets indoors during spraying.  Although pets that remain outdoors could be exposed to small amounts of Anvil 10+10, they are not expected to experience adverse health effects from the spraying.  There are many pesticide products (e.g., flea collars, pet shampoo, dips) containing similar ingredients that are used directly on pets to control ticks and insects.
  • If clothes or outdoor items are exposed during spraying, wash them with soap and water.
  • No special precaution or waiting periods are needed for outdoor swimming pools.

It remains critically important for people in communities at critical, high and moderate risk for EEE to continue to take personal precautions against mosquito bites. These steps include using EPA-approved bug spray, wearing long sleeves and pants outdoors to reduce exposed skin, and cancelling outdoor activities in the hours from dusk to dawn when mosquitoes are most active.

Why aerial spraying?
In situations where there is a high risk of human disease, the state’s response plan recommends consideration of the use of an aerial pesticide spray in the evening and overnight hours to reduce the number of infected, adult mosquitoes in the specific areas of high risk. Many breeding areas of high concern are not accessible by truck-mounted ground sprayers.

It should be noted that although the aerial spraying is considered necessary to reduce human risk, it will not eliminate risk. It is critical that residents protect themselves from mosquito bites by staying indoors during peak mosquito hours, applying insect repellent when outdoors, draining standing water where mosquitoes breed, repairing screens, and protecting animals and pets.