They can grow to the size of an adults' thumb and deliver a sting so painful that one entomologist described it to The New York Times as "like having red-hot thumbtacks" being driven into their flesh. And now experts say they've been spotted in the United States for the first time, the Times' reported.

They are known to some as the Japanese giant hornet, the yak-killer hornet, or sparrow wasp. But some have taken to calling them by another more ominous name; murder hornets. The New York Times says the insects have been spotted in Washington state.

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The hornets are most active from July to October. According to an article from the Weather Channel, the hornets attack beehives and kill the bees by decapitating them. Todd Murray, a Washington State University Extension entomologist and invasive species specialist, said:

As a new species entering our state, this is the first drop in the bucket. Just like that, it’s forever different.

We need to teach people how to recognize and identify this hornet while populations are small, so that we can eradicate it while we still have a chance.

A video by YouTuber Coyote Peterson getting stung by one of these giants in 2018 began trending again after the Times' story appeared this weekend. The sting causes some intense pain and swelling. You can watch the daredevil brave the "murder hornet" sting below: