Consider This: What is the best mosquito response plan for Harvard?

Eastern Equine Encephalitis (EEE) is a rare but serious mosquito-borne disease. Between 2014 and 2018 there were no reported cases of EEE in humans in Massachusetts; however in 2019 there were 12 human cases in the state. The disease tends to happen in two- to three-year cycles. The state’s Department of Public Health (DPH) and the Department of Agricultural Resources (MDAR) have increased surveillance in 2020 for EEE and West Nile Virus (WNV).

DPH has asked each town to prepare an arbovirus (mosquito-borne disease) response plan.

Options for towns include:

• Personal protection. Avoid outdoor activity during times of day with increased mosquito activity, use mosquito repellents containing an Environmental Protection Agency-approved active ingredient, and wear long-sleeved clothing.
• Control of mosquito larvae (larvicide). Towns can use BTI (Bacillus thuringiensis, subspecies israelensis) to kill some species of mosquito larvae.
• Roadside spraying. Harvard could join the Central Mass Mosquito Control Project (CMMCP) to contract for roadside spraying to help control mosquitoes. Spraying is done from trucks and reaches approximately 300 feet from the road, with a clear line of sight. A cost estimate for such spraying in Harvard is approximately $90,000 per year, with a minimum three-year contract.

Aerial spraying is only conducted at the direction of the state.

Is roadside spraying the right solution for Harvard?

The Board of Health opposes roadside spraying. Our reasons are as follows:

• The anti-mosquito pesticide mist can travel approximately 300 feet from the road, but the actual distance can be substantially less due to dense vegetation, buildings, and weather conditions. Many houses in Harvard would not be reached by the spray.
• The spray kills only the adult mosquitoes that are active at the time of spraying; it has no impact on eggs or larvae. Additional mosquitoes develop (larvae to pupae to adult) in the days following spraying.
• The majority of land in Harvard is greater than 300 feet from a road and would not be reached by roadside spraying. Some mosquitoes travel an average 1 to 3 miles; they can travel from untreated land to your backyard.
• Spraying has limited effectiveness. Residents must still take personal protection measures.
• Insecticides kill non-target species, including honey bees and dragonflies. U.S. Fish and Wildlife does not allow spraying at the Oxbow National Wildlife Refuge due to this concern (among others).

Our recommendations

The Board of Health recommends the following actions.

• Use personal protection:
  • Wear an effective repellent outdoors between dusk and dawn.
  • Wear long sleeves, long pants, and socks between dusk and dawn.
  • Avoid outside areas with obvious mosquito activity.
  • Repair screens.
• Reduce population of larval or immature mosquitoes:
  • Remove standing water around homes.
  • In private ponds and water features, use BTI (Bacillus thuringiensis isrealensis), which is approved for use in organic farming; the town should research using BTI in town-managed fire ponds and catch basins.

There is no silver-bullet solution that will eliminate mosquitoes. Residents should adopt effective personal protection strategies and should act now to reduce standing water around the home, fix screens, and find a repellent that works for each family member. We need to take these precautions until the first killing frost.
   

Sharon McCarthy, Chris Mitchell, and Libby Levison are the appointed members of Harvard’s Board of Health.