Asian giant hornets are huge bee murderers with powerful stings, and they have reached North America.
Asian giant hornets (Vespa mandarinia) are the biggest hornets in the world. Native to Asia, these pests have been identified in Washington State since 2019 and several other potential sightings have prompted quarantines and requests to the public to be on the lookout.
These hornets have stingers that are twice as long as honey bee stingers and they contain a lot of venom. They can also spray venom into your eyes. Being stung by several of these monsters at the same time can kill you.
Asian giant hornet identification
Asian giant hornets have a 3” wingspan. The queen averages just under 2” in length while the workers and drones are slightly smaller. Their heads and forelegs are pale orange with a brown base. The body has alternating brown or black and orange bands.
Asian giant hornets are commonly misidentified as European hornets (V. crabro) and Eastern cicada killers (Sphecius speciosus) in the U.S., and Oriental hornets (V. orientalis) and Asian hornets (V. velutina) in Europe.
Asian giant hornet lifecycle
Asian giant hornets are most commonly found in forests and hilly areas. They feed on large insects, tree sap, and honey bees. Mostly honey bees. A group of Asian giant hornets can kill an entire colony of honey bees in just a few hours. Your average honey bee colony contains tens of thousands of bees.
Asian giant hornets use vision, sound, and chemicals to communicate. They are the only hornets that use scent markers to guide the colony to food sources. Sadly, honey bees are their most common food source. But a single hornet cannot attack a honey bee hive. The bees will surround the hornet and use their wings to generate so much heat and carbon dioxide that it kills the hornet. In most cases, however, these hornets attack hives in concert.
They build their nests in tree cavities, around rotting tree roots, and in rodent and snake holes. These holes can be 6” to 24” deep. The comb is formed into towers that can be 18” tall and wide. Old towers are abandoned and left to rot, and new towers are built alongside the old ones.
Reproduction and castes are similar to honey bees, except that Asian giant hornet hives may contain dozens or even hundreds of queens. The highest-ranked queen gets first dibs on any available sap, followed in ranking order by other queens. Drones provide semen and workers collect food. They also fiercely protect whatever they consider theirs.
Mated queens go in search of new nesting sites in mid-spring. Once a site is found, she creates a small hive where she will lay 40 or so worker eggs. These workers emerge in mid-summer. By this time, the hive is likely to have 500 cells and 100 workers. This is when unmated queens disappear. By the end of summer, cells are filled with eggs. When the eggs hatch, Asian giant hornet larvae tells their caregivers it’s dinner time by scraping their mandible against cell walls. When they have eaten their fill, they spin cocoons around themselves.
Reporting Asian giant hornets
If you live in Washington State and see an Asian giant hornet, please report it to the Washington State Department of Agriculture (WSDA) immediately. Otherwise, contact your local Extension Office. And you may want to invest in one of Dennis Jaffré’s new Asian giant hornet traps.
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