Greener Ways to Avoid Acton’s Mosquitoes

by Chris Edwards, Chair, Green Acton Toxics/Pesticides Subcommittee

While you’re enjoying the outdoors in Acton, it’s important to protect yourself and your loved ones from being bitten by mosquitoes, ticks, fleas, and other insects, since these critters can carry harmful viruses, bacteria, and parasites. Unfortunately, some of the most effective repellents have environmental and toxic effects during manufacture and after application. This guide offers a “greener” approach to avoiding mosquito bites. Future posts will provide tips on preventing tick bites and treating lawns and other outdoor areas in environmentally friendly ways.

The Dangers of Mosquito Bites in Massachusetts

Beyond the itching and soreness that accompany mosquito bites, in Acton there is little chance of contracting a severe illness. In Massachusetts, mosquitoes can occasionally transmit rare diseases, such as West Nile virus (WNV) and Eastern equine encephalitis (EEE). Although WNV is the most common mosquito-borne illness in the continental U.S., in Massachusetts only 12 cases were reported in 2020. Fewer than 1% of people who contract WNV get a severe infection, but 20% of those who do contract the virus show symptoms, such as fever, body aches, nausea, or rashes, and the illness can be fatal. Nonetheless, for people in Acton, the likelihood of contracting WNV — let alone getting a severe case of it — is low.

EEE is also very rare in Massachusetts. Since the virus was first identified in Massachusetts 84 years ago, there have been only 115 cases, mainly in Bristol, Plymouth, and Norfolk counties. In 2020, there were only 5 cases, including one fatality. (Find current risks for both diseases here.) In summary, there is a small risk of contracting a major mosquito-borne illness in Acton, but it’s worth protecting yourself from the risk and the annoyance created by mosquito bites.

Avoid Mosquito Bites Safely and Protect the Environment

Before reaching for a repellent, consider these factors: the likelihood of disease when exposed to mosquitoes, the ecological cost of manufacturing and using chemical repellents, and your ability to make simple behavioral choices to avoid mosquito bites. In other parts of the world, mosquitoes carry malaria, which in 2020 killed 220,000 people, mostly children on the African continent. In malaria-prone areas, the most effective protection possible is critical: a slightly greater environmental cost of using a chemical repellent (e.g., DEET) may be offset by the significant personal risk of deadly disease from a bite. In Acton, because your chances of severe infection are quite small, you can get good protection from bites while minimizing toxicity. Simply use a combination of these strategies:

• Choose your outdoor time wisely. The best way to prevent mosquito bites is to avoid mosquitoes when they’re most active. Mosquitoes function best at 80ºF, become lethargic at 60ºF, and cannot function below 50ºF. They quickly dehydrate in hot and sunny weather. Mosquitoes will be most prevalent during their feeding times — at sunrise, sunset, and night.

• Take precautions in areas with standing water.

Acton and its surroundings are fortunate to have extensive conservation land, including wetlands. Mosquitoes are attracted to standing water, so avoid these areas if possible, visit them only in hot or cold weather, or use safe repellents (discussed below).
• Avoid products that attract mosquitoes. Besides the CO2 you exhale, mosquitoes are attracted to specific components in your sweat. People who seem to be “mosquito magnets” may have natural attractants in their sweat. Sometimes a quick shower makes you less attractive. Also, avoid fragrances — including those in soaps, shampoos, and other personal care products — many of which can attract mosquitoes.
• Dress appropriately. Mosquitoes and other insects are more likely to detect you if you wear dark clothes, so wear light-colored clothes with tightly woven fabric. Wear long-sleeved shirts and pants. Cover up as much as possible, including tucking your pants inside your socks. You can also use inexpensive netting that fits over your clothes and head.

• Use a fan or netting.

Very simply: run a fan or use netting if you are sitting outdoors. In addition to making it more difficult for mosquitoes to fly toward you, a fan will disperse your most potent personal attractants: CO2, lactic acid, sweat, and fragrances. There’s no known relationship between wind speed from fans and repellent effects, so a medium setting should suffice.
• Be reasonable with repellents. It can be tempting to just “spray away” mosquitoes by using any repellent found on the shelf of your grocery store. However, in Acton, you can use products that have minimal toxic health and environmental impacts.

Safe and Safer Alternatives

The EPA (U.S. Environmental Protection Agency) and other reputable sources recommend oil of lemon eucalyptus (OLE), which seems to be the best safe-repellent choice. Do not confuse OLE with products listing lemon eucalyptus essential oil as an ingredient; like its sister oil, citronella, it is not an effective repellent. Both OLE and lemon eucalyptus oil are processed by extraction from leaves of the lemon eucalyptus tree, but OLE contains concentrations of the active ingredient responsible for its repellent property.

Here’s a complete list of EPA-approved repellents against mosquitoes and ticks. But consider these factors that are context for EPA approval: even the best science is incomplete; toxicology is a young and evolving science; the carbon and overall ecological cost of manufacturing and using repellents can be notoriously difficult to calculate; industry has a stake in influencing EPA decisions; and previously unknown toxicities for common household products are being discovered every year. It’s easy to forget that the first widely used synthetic insecticide, DDT, was sprayed in homes and on farms and landscapes for about 30 years before its adverse effects on the environment, wildlife, and human health led EPA to ban its use.

Other common insect repellents include picaridin, IR3535, 2-undecanone, and permethrin. These repellents vary a great deal in their effectiveness. Although they may be advertised as “natural” or made from natural products, their ingredients are concentrated or synthesized versions of natural compounds. When synthesized as insect repellents, these compounds are usually used in much higher concentrations than exist in nature, so “natural occurrence” does not guarantee safety. As an analogy, iron, calcium, vitamin A, and vitamin D can be useful when prescribed for specific disorders. However, very large doses can be toxic or even fatal. Concentration matters.

DEET: Popular but Problematic

The most popular — but possibly the most controversial — of the EPA-approved mosquito repellents is DEET (look on the label for N,N-diethyl-meta-toluamide). According to EPA, one-third of the U.S. population uses DEET annually. Initially developed for the U.S. Army during World War II, DEET is chemically synthesized. The EPA recommends its use to mitigate the risks of WNV and encephalitis from mosquitoes and Lyme disease from ticks.

However, there are lab and animal studies linking DEET to neurotoxicity, kidney disorders, and developmental disorders. Although studies have not shown lasting damage in humans, cases of epileptic seizures have been reported in children, and skin inflammation can occur in adults using formulations that are more than 30% DEET. Ingestion can be harmful in any form, including accidental inhalation of sprayed applications. Given its widespread use and accumulation in wastewater, DEET’s effects on human health and biodiversity need further research.

If you must use a product containing DEET, do not apply concentrations of more than 30% on adults and use the lowest available concentration on children (some products contain as little as 4% DEET). Do not let children apply DEET products themselves. Use DEET only on exposed skin (not eyes or mouth) and on clothes, but do not apply DEET underneath clothing. Do not use DEET on open cuts or wounds. Wash treated skin with soap and water when you return home. DEET is dangerous to pets, so keep it away from them. Other information on DEET can be found at Beyond Pesticides.

Beyond Pesticides, a nonprofit organization, has a particularly useful section that provides extensive information about how pesticide use affects health and the environment. In particular, see the section on mosquito repellents.

Avoid Synthetics in Your Yard

Don’t be taken in by lawn services that advertise “safe” insect repellents: they typically use what they call “natural” products, such as synthetic pyrethroids, including bifenthrin. When repellents are widely sprayed on lawns or gardens, they may have adverse effects on bird and insect populations, and they can reach the groundwater that eventually leads to your faucet. A future article will discuss “greener” ways to take care of your lawn, yard, and gardens.

By choosing an eco-friendly approach to repelling mosquitoes this — and every — summer, you can defend yourself against bites while protecting your family, our community, wildlife, and precious natural resources from toxic chemicals.