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Bug experts: 'Do not be afraid' of large cicada killer wasps

These wasps are big, but don't confuse them with the recently sensationalized Asian "murder hornet."

Notoriously large Eastern cicada killer wasps have re-emerged in Connecticut in numbers higher than typical this summer. Scientists and local exterminators say they’ve been getting more calls from concerned residents mistaking the wasps for the giant Asian hornets, but say there’s no reason for humans to be afraid of these native wasps.

Though as large as a murder hornet — up to 2 inches in length — and almost as menacing looking, these wasps only prey on the annual cicadas for which they are named and are not likely to attack or sting humans unless seriously provoked.

In fact, Connecticut Agricultural Experiment Station, or CAES, Associate Scientist Gale Ridge says humans can walk through swarms of these wasps, or even sit among them, and not be attacked or stung.

“These are not like hornets or yellow jackets, which are known to attack humans,” she said, describing the cicada killers as “solitary gentle giants” despite their vicious-sounding name. “The only time you would have a stinging situation is if the insect considers itself in dire peril and sees no way out," such as being stepped on.

“These insects like to stick to themselves, and they are singularly focused on their sole mission in life," she said, explaining their mission as burrowing nesting holes and finding unsuspecting cicadas to feed to their offspring.

Ridge said that process works something like this: Every summer, the cicada killers come out of their underground nests, which are typically 10-inch-deep holes their mothers dug the prior summer, timing their appearance with the emergence of annual native cicadas in late July into August.

Males, who have no stingers and are “very acrobatic,” emerge first to establish territory and joust one another while they wait for female wasps to emerge. Then, when females hatch, males fight to mate with them.

During this time, homeowners often will see the wasps hovering above and zooming around their lawns, with males zipping about and dive-bombing one another to fight for territory, while female wasps begin to dig nesting holes — a single wasp can dig up to as many as 10 holes, Ridge said — in which to lay its eggs.

Before laying eggs, however, female wasps, who do have a stinger, need to hunt food for their soon-to-be babies in the form of one unsuspecting cicada.

“The wasp will fly into the trees, isolate the cicada, paralyze it by stinging it and then fly back with the cicada, if it's not too much. Often, the cicadas and (wasps) plunge to the ground and the female drags it into the hole," Ridge said, “It will then literally stuff the cicada” into its nesting tunnel to lay an egg on. The cicada, though paralyzed, remains alive, becoming a living food source for the wasps’ offspring before they pupate, overwinter and hatch the following summer.

When the grown wasps emerge from the same tunnels a year later, they can, and often do, give some homeowners a scare, Ridge said. That seems to be the case this summer, as increasingly more homeowners have been calling Ridge and CAES to ask about the large wasps they are suddenly spotting in their backyards.

“We want people to know they are technically harmless,” Ridge said. “They are not aggressive. ... They are also not the Asian giant hornet. ... I've never known anyone to be stung by them and I've been in the field for more than 20 years."

Though she couldn’t cite just one single reason for the increase in concerned callers, she said there is likely a variety of factors, ranging from a new, widespread fear of “murder hornets” to more people simply working from home due to the coronavirus pandemic and who are now, maybe for the first time, actually observing their yards.

“It’s a collision of two worlds,” Ridge continued. “People have been made aware of this reporting of the ‘murder hornet’ and are keeping their eye out for them and more people are also home.”

She added that last winter was exceptionally mild and did not get cold enough to kill the vulnerable wasps underground. "Usually wintertime will do a selection where the sturdiest and strongest will survive and the weaker ones will die," she said. "But that didn’t happen this year.”

Calling in pest control

Guardian Pest Control head of operations Fred Colby added that this year’s dry summer could be contributing to creating perfect conditions for the wasps to nest in people’s yards.

“They like to dig in sandy, patchy areas with no grass and a lot of dirt,” Colby said. “The more dry spots there are in the yard, the more places they will have to dig.”

He estimated that the amount of calls made to his company to exterminate the wasps was about 20% higher than normal this year. Usually, he said, he will receive 250 to 300 calls over the course of a summer, whereas this year he already has gotten more than 300.

“It’s the large size of the wasps and the amount of them, that are provoking people to call,” Colby said. “People can get inundated with them, with dozens of them swarming through their yards. And they get scared. These are giant wasps and they look very intimidating.”

In all his summers working as an exterminator for Guardian, Chance Brockett said he, too, has never seen as many cicada killer wasps as he has this year.

Brockett, who specializes in exterminating the wasps, said he spends at least two or three full work days in an average week exterminating cicada killers throughout the region.

“I’ve been very, very, very busy,” he said, while overturning rocks in a Madison yard this past week, searching for the wasp’s signature nesting burrows. “Just before I got here, I was in a yard where I found 400 (nesting) holes. That’s just what I’m seeing this year.”

To exterminate the wasps, an exterminator technician, such as Brockett, will need to find and “dust” every single nesting hole with a white powder that attacks the wasps’ nervous system and kills them. In cases where there are as many 400 burrows in a single yard to dust, Brockett said the process can take a couple hours, especially as he typically gets onto his hands and knees to look for the not-so-obvious nesting holes.

Besides some homeowners simply having an aversion to wasps, Colby said many residents will call for extermination because they are either deathly allergic to wasps — as was the case for a Madison customer the two visited Wednesday — or because they have kids, as was the case for a customer in Old Lyme this past week.

“They can become a nuisance pest,” Colby said. “And control is warranted when you have a playground area or a sandbox, where kids are playing and they are out here barefooted running around.”

Ridge argued, however, that it is not always necessary to exterminate the wasps if the homeowners can bear their presence. Instead, she urged homeowners to pay attention to why the wasps are in the yard in the first place.

“If they are in your yard, they are speaking to you, they are speaking to the homeowner — it means that the ground is in bad shape, the soil is in poor condition,” she said. “They only burrow in soil that has been compromised, soil that is broken up, has low vegetation, is dry, sandy and low in organic content.”

She said if homeowners focus on seeding and getting their soil back to a healthy state, cicada killers will not return the next summer, “And that is the best pesticide, because you’re not killing the wasps.”

Colby agreed, saying, “The only long-term resolution that we always recommend to homeowners is, fix your soil, make sure that you till it. Get all the sandy dirt loose. Re-sod if you need to. If you want us to come each year to do this, call us each year, that’s fine. But if you want a final, long-term resolution, you gotta fix your ground.”


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