How mosquito experts protect themselves in the summer

Few things ruin an evening outdoors faster than the realization that you’re being eaten alive by mosquitoes.

These biting insects, which can transmit diseases like dengue, malaria, and West Nile virus, “remain the most dangerous animal on Earth,” said Adrian Vasquez, an assistant professor in the biology department at Mercer University who studies mosquitoes. And avoiding them is becoming more important than ever, since research suggests that mosquito populations are expanding across the United States, he added.

Existing mosquito species are spreading to new areas, and invasive species from other countries have taken up residence in the U.S. There’s also evidence that mosquito season may be getting longer due to the rise in global temperatures, and climate change is also enabling some mosquito-borne diseases, such as dengue, to spread into new areas.

Even if you live in a place where these types of disease are less likely, mild bites can be itchy and uncomfortable, and some people develop large allergic reactions to them.

It’s almost impossible to avoid mosquitoes entirely — even if you spend all summer indoors — but there are steps you can take to minimize your contact. The Washington Post asked eight mosquito experts how they personally avoid getting bitten during the warmer months.

Here are the strategies they recommend.

Experts said regularly surveying your property for standing water is a crucial way to curb mosquito numbers. “I go around my backyard and my front yard and maybe a little bit around in my neighborhood to see if there are any obvious areas with puddles of water,” said Anandasankar Ray, a professor in the Molecular Cell & Systems Bio Department at the University of California Riverside who studies the effectiveness of mosquito repellents.

Bird baths and abandoned pools are likely sources, but you might also discover standing water in old tires, leaf litter, or the bases of potted plants. Most of a mosquito’s life cycle occurs in water, “so by removing any stagnant water, you remove potential breeding sites,” said Raymond Cloyd, a professor and extension specialist in horticultural entomology at Kansas State University.

These puddles “can be really small,” added Ray; they might form on items left in your yard that collect rain, like a pool float, small toy or piece of garbage. “A lot of people don’t realize that mosquitoes can breed in sometimes very little moisture,” said Vasquez, who said the amount of water that fits in a plastic water bottle cap can be enough to support the next generation.

For standing water that can’t be emptied — say, your yard has a fish pond — a larvicide containing Bti (Bacillus thuringiensis subspecies israeliensis) may be helpful. These products contain a bacterium that kills mosquito larvae in water and are “very safe,” said Laura Harrington, a professor of entomology at Cornell University.

The Bti bacterium produces toxins that specifically target mosquito, blackfly, and fungus gnat larvae and is not harmful to other insects, humans, birds, fish, or other animals.

Two readily available products are Mosquito Bits, which are sold as granules, and Mosquito Dunks, doughnut-shaped devices that dissolve when placed in water. The latter “look like tiny little hockey pucks,” said Ray. “I just put them in drains or water bodies where I think the mosquitoes might breed.”

These products generally release the bacterium for around a week, “and then if you keep repeating that intervention, you can prevent mosquitoes from emerging,” said Gonzalo Vazquez Prokopec, a professor in the Department of Environmental Sciences at Emory University who studies vector-borne diseases.

Insect repellent is another important tool to prevent bites, experts said. “I think that there is a misunderstanding about the safety of repellents,” Harrington said. “There actually are some very safe repellents on the market.” The EPA has a search tool of registered insect repellents, meaning the active ingredients have been evaluated and found to be safe.

In terms of efficacy, DEET is “the best thing to prevent biting,” said Jeff Riffell, an endowed professor in biology at the University of Washington. This synthetic repellent was developed by the U.S. Army in the 1940s and suppresses scent, so mosquitoes have a harder time smelling humans.

Some people prefer not to use DEET due to older reports of adverse health effects after ingesting it, but the EPA’s safety reviews concluded the ingredient does not pose a health concern to adults and children if used properly — applied only to exposed skin and avoiding broken skin and your eyes and mouth.

Other repellents experts said they use include picaridin, which can prevent mosquito and tick bites, and products made with oil of lemon eucalyptus.

Oil of lemon eucalyptus “really repels the mosquitoes from a distance,” Riffell said, “the only problem is that you have to kind of keep using it over and over.” According to the CDC and American Academy of Pediatrics, this product should not be used on children under the age of 3.

When spending time outdoors in mosquito-prone settings, such as while gardening or doing yard work, “I try to wear long pants and long sleeves, then that leaves less skin that I have to put repellent on,” said Jerome Goddard, an extension professor of medical entomology at Mississippi State University. The goal is “just trying to cover up the skin as much as possible,” added Harrington.

Applied to clothing, a synthetic pyrethroid insecticide called permethrin can also effectively repel insects, experts said. “It’s a fantastic way to prevent mosquitoes from biting you,” Riffell said. You can purchase clothes that have been pretreated with permethrin or apply it yourself.

“I personally have done that when I was going on a trip to Brazil,” said Eva Buckner, an assistant professor and state extension specialist at the UF/IFAS Florida Medical Entomology Laboratory. “I treated all my clothing with the permethrin spray just to protect against not only mosquitoes, but ticks.”

Using permethrin on just a few items can make a difference if you don’t want to spray all of your clothes. “What I do is I spray my hat, I’ll spray the bottom of the hat, and then I’ll spray my sleeves and then my shoes,” Harrington said.

There’s a reason you’re less likely to collect mosquito bites on windy days: “Mosquitoes aren’t wonderful flyers,” said Buckner, so fans can be a helpful deterrent. Bigger fans will make a bigger impact, noted Cloyd, but even smaller fans that are strategically aimed can help minimize bites in outdoor entertaining areas. “If I have guests over for dinner on the patio, [I’ll use] fans that are placed under the table,” said Harrington.

Experts also suggested spatial repellents, or devices that create a protective radius. “If I’m sitting down somewhere, like a patio or hanging out in a balcony, and if there are lots of mosquitoes around, what I will do is use a mosquito spatial repellent,” said Ray, such as the brand Thermacell. These devices, also called spatial emanators, often have rechargeable batteries and “emit just a small amount of a chemical that will deter the mosquitoes from coming into an area,” Harrington said.

“If you’re going to be eating outside and staying in one place, I think that they can create an effective bubble of protection around you,” Buckner said.