‘Murder hornets’ and other dangerous summer pests to beware

Washington was the first state in the country to bear the brunt of the COVID-19 pandemic. Now, the Evergreen State is facing another invasive pestilence: the “murder hornet.” 

Its real name is the Asian giant hornet (Vespa mandarinia), and it’s been spotted in several areas in the Pacific Northwest. It’s the world’s largest hornet—the size of a baby carrot—up to 2 inches in length, with a 3-inch wingspan and a venomous quarter-inch stinger. 

It was dubbed the “murder hornet” for its ability to strike quickly, decapitate its prey with its large mandibles, and then carry home the body parts to feed to its larvae. A single murder hornet can wipe out as many as 40 honeybees per minute. A raiding party of a few dozen hornets can decimate a hive of tens of thousands of honeybees in a few hours. 

Unlike honeybees, which lose their stinger and die after one strike, a hornet can sting and sting again. Their sting is extremely painful and, when a murder hornet does sting, they release a pheromone that attracts more murder hornets to the scene. This ability to make multiple painful stings, plus their potent venom, is why they’re particularly dangerous—even deadly—to humans, especially if the hornets attack in numbers. 

Murder hornets reportedly kill as many as 50 people in Japan every year. In 2013, when murder hornet populations were abnormally high, they killed 42 people in a single Chinese province, according to a report from National Geographic. 

Fortunately, only a handful of murder hornet sightings have taken place in Washington and British Columbia. Entomologists and state officials are hopeful that this invasion (unlike that of the coronavirus) can be stopped before making a foothold here. But if not, then Americans and, especially, the already-threatened honeybee will be in danger.

Summer pests to beware

Though it’s highly unlikely that you’ll run into a murder hornet any time soon, many other insects and pests will arrive to add even more difficulties to our numerous list of problems this year. 

“It goes without saying that this is a sensitive and uncertain time not only across our country, but across the globe,” said Cindy Mannes, vice president of public affairs, National Pest Management Association (NPMA), Fairfax, VA. “With people spending more time in their homes and yards, they may be surprised at how much pest activity they begin to notice.”

Pest populations (unlike viral populations) are only increasing at this time of year. So, “it’s important to stay vigilant against insects and rodents, which can contaminate food, inflict harmful bites and stings, transmit disease, and damage property,” Mannes said. 

According to NPMA entomologists, ongoing warm and wet weather has triggered insect populations to spike early, which will enable them to thrive throughout spring and summer across most of the United States. 

“These conditions allowed vector pests such as ticks (responsible for the spread of Lyme disease) and mosquitoes (common vectors of West Nile virus, Zika virus, and Eastern equine encephalitis) to get a jumpstart on activity,” said Jim Fredericks, PhD, chief entomologist for the NPMA. “With more warm and wet weather predicted for summer across most of the US, we’ll likely see these populations, and others, rapidly expand.”

How will this affect different parts of the country? “Damp conditions predicted for the Northeast, Southeast, and South Central regions this spring and summer will enable termite, cockroach, and ant populations to take hold and thrive,” Dr. Fredericks said. “In areas expecting less moisture this season, stinging insects will also pose a significant threat, as families will be spending more time outdoors, increasing their likelihood of exposure to these dangerous pests, which send over 500,000 people to the emergency room every year.”

For further specifics about insect involvement in different US locations, the NPMA has released its “Spring/Summer Bug Barometer” forecast, which predicts a spike in moisture-loving pest populations across most of the United States this season. Here’s what the NPMA’s Bug Barometer says you can expect in your neck of the woods: 

Northwest (WA, OR, ID) The Northwest had a warm and wet fall, and a chilly and wet winter. Humid conditions occurring throughout spring and summer in the eastern part of this region will encourage stinging insect and tick populations to flourish. Warm and wet conditions in the western part of this region may also contribute to increased mosquito populations.

Southwest (CA, NV, UT, AZ) This region had a cold and dry winter, though with excessive precipitation late in the season. Cooler, wetter conditions throughout the spring and summer will likely drive ants indoors. Also, expect an increase in cockroach and stinging insect populations throughout the Southwest.

South Central (NM, TX, OK, AR, LA) This region experienced a warm and damp winter, with unexpected snow in some areas. A warm spring followed by a warm and wet summer across the entire South Central region is expected to result in an increase in pest pressure, specifically for termites, ticks, and cockroaches. (Pest pressure is the likelihood of pest encounters or infestations in a given region, according to NPMA.)

North Central (MT, WY, CO, ND, SD, NE, KS, MN, IA, MO) After blizzard conditions throughout the winter, warm and dry summer conditions in the south of this region will spur ant populations to thrive, and could mean more exposure to stinging insects. While cool conditions in the north of this area may delay tick activity, increased precipitation will create ideal growth conditions for mosquito populations.

Great Lakes and Ohio Valley (WI, IL, IN, MI, OH) This area had a very snowy and rainy winter with bitingly cold temperatures. Throughout spring and summer, warm and wet conditions across the entire region will contribute to an increase in tick pressure and may result in greater ant populations.

Southeast (MS, TN, KY, AL, WV, VA, NC, SC, GA, FL) It was warm and wet throughout the entire winter in the Southeast. A mild and rainy spring will create conducive conditions that allow mosquito and termite populations to thrive. Summer conditions in southern Florida may also cause a spike in cockroach and ant pressure. Notably, the 17-year cicadas will return this year—with as many as 1.5 million of them emerging per acre—but this will cause more of a noise problem than anything. 

Northeast & New England (MD, DE, PA, NJ, NY, CT, RI, MA, VT, NH, ME) The winter here started with early snows and ended with rain. A warm, dry spring followed by a warm and wet summer will contribute to an increase in tick activity. Damp conditions throughout the summer will also provide ideal conditions for ants (specifically, carpenter ants) and termites to thrive.

Tips to prevent or avoid summer pests

Take note that vector pests, like mosquitoes and ticks, don’t spread the SARS-CoV-2 virus. But, they do spread many other dangerous diseases. Mosquitoes are the leading vectors that transmit infections to humans. They’re responsible for spreading malaria, Zika virus, West Nile virus, Eastern equine encephalitis, chikungunya, yellow fever, and many others. Ticks, on the other hand, transmit Lyme disease—the most common vector-borne infection in the United States—as well as many other infections, including Rocky Mountain spotted fever, babesiosis, ehrlichiosis, and anaplasmosis.

To prevent these diseases and others, the NPMA offers tips to avoid these pests: 

Mosquitoes. These pesky bloodsuckers are mainly active around dusk and dawn, so avoid the outdoors at those times to reduce the likelihood of getting bitten. When you do go outside, use repellent on exposed skin wherever mosquitoes are likely to bite. The most effective repellents contain DEET in concentrations up to 35% (greater concentrations don't offer better protection). 

Wasps. Don’t swat at wasps as it increases the likelihood of an aggressive reaction. Check plants and trees for wasp nests to keep these stinging insects from making your yard their home.

European hornets. Because these hornets can be active at night, change exterior lights to yellow bulbs (“bug bulbs”) to reduce this insect’s attraction to your home or yard.

Ticks. To prevent tick bites, wear long pants, long-sleeved shirts, and closed-toe shoes when outdoors, especially in wooded areas or tall grasses. When hiking, do your best to stay in the center of trails, away from vegetation where ticks may be hiding and waiting to hitch a ride. In your yard, keep grass cut low and remove weeds, woodpiles, and debris, which can attract ticks and other pests. Keep shrubs and bushes well pruned, particularly around patios and play areas. 

Ants. Keep tree branches and other plants cut back from the house, as ants often use these branches to enter homes. Inspect potted plants inside the home for signs of nesting and remove the plants at the first sign of an infestation. Rinse out empty soft-drink containers and store them away from the home.