Asian giant hornet (2019)

Michael R. Bush, Christopher Adams, and Sven Spichiger
Revised: 
March 2021

Vespa mandarinia

Several invasive hornets, including the Asian giant hornet (AGH), have been intercepted in ports throughout the Pacific Northwest. In 2019, AGH was confirmed in and eradicated from British Columbia, Canada. In December 2019, WSDA responded to a public sighting and captured this hornet near the border of Washington State and British Columbia. During the 2020 season, citizen scientists, together with WSDA/WSU staff, placed over 2,500 hornet traps in northwestern Washington. In October of 2020, these traps helped WSDA locate and eradicate the first AGH nest in North America. WSDA continues to pursue and eradicate any reports of the Asian giant hornet.

Description and damage This hornet resembles our native yellowjacket wasps, but adults can be nearly 2 inches long. Adults have a distinctly yellow-orange head with prominent black eyes, black thorax and black/yellow striped abdomen. This hornet preys on other insects, gathers tree sap and raids the colonies of other bees and wasps for protein spoils. In late summer and throughout the autumn, this hornet will invade honey bee colonies and hives, decapitate bee workers and then feed on the colony brood and provisions. These hornets can sting humans and animals, but only when their nests are disturbed. If you suspect that you have a colony, do NOT attempt to remove or eradicate it. AGH will aggressively defend its own nest. Furthermore, this species of hornet will sting in self-defense, so do not handle any live specimen! The sting of AGH is more dangerous than that of other stinging insects in Washington since it can sting multiple times and deliver a larger dose of venom. Seek medical attention immediately if stung multiple times.

Biology and life cycle This hornet nests and forms colonies often in underground chambers early in the spring. During the summer, the nest expands in size and number. Between July to October homeowners are most likely to encounter foraging adults.

Pest monitoring If you suspect you have found a honeybee colony damaged by this species, or suspect you have encountered this large hornet, please report the finding to the State Department of Agriculture or local university Extension office. If safe, attempt to photograph the specimen and note what direction the hornet flies when it leaves. When confirmed as an invasive hornet of concern, these state agencies will respond and work with you to eradicate this pest as soon as possible.

For further information:

McGann, C. 2019. Pest Alert: Asian giant hornet. WA State Department of Agriculture Ag Briefs. https://wastatedeptag.blogspot.com/2019/12/pest-alert-asian-giant-hornet...