down and cleared out. about the size of a basketball, the first known nest of its kind in the u.s., discovered inside a tree north of seattle. >> i took a step back and realized we were standing right under the nest. we had tracked her straight back to where she had came from. >> reporter: the discovery was weeks in the making. entomologists using dental floss to attach an electronic tag to a so-called murder hornet that led them back to the nest, which they sealed off. then vacuuming out over 100 hornets. first found in the u.s. only several months ago, the giant hornets are native to asia. they can be deadly to humans, killing up to 50 people in japan each year. and a massive threat to honeybees. they kill them by decapitation. >> only a few of these hornets can take out 30,000 healthy honeybees in a matter of a few hours. >> reporter: we're not out of the clear yet. entomologists saying there's a very good possibility there could be more nests. beekeepers hoping that is not the case. >> zohreen, thank you.