When the first Asian giant hornet (Vespa mandarinia) was found in Washington State and in British Columbia, Canada, in December 2019, it triggered a series of media reports because this newly arrived invasive pest from Asia is particularly vicious.
The Asian giant hornet, also called Japanese giant hornet, is the world’s largest hornet. It is also referred to as “murder hornet” because it can destroy an entire honeybee colony within a couple of hours. The venom from its sting can also cause severe reactions in people sensitive to bee stings.
That said, you can be reassured that it is currently highly unlikely that you will find an Asian giant hornet on a hike or in your yard. There have been no sightings of the Asian giant hornet in other parts of the United States and Canada, and the situation is being closely monitored nationwide.
If, however, based on the information below, you think you have positively identified an Asian giant hornet, send a photo to your local Extension Office.
How to Identify Asian Giant Hornets
The most striking feature of the Asian giant hornet is its size. The queen is about two and a quarter inches long, and the workers are about one and a half inches long. Their wingspan can reach up to three inches.
The head of the Asian giant hornet is uniformly yellow. Its upper body (the thorax) is black, and its abdomen has plain stripes or bands of yellow and dark brown or black. The adults have narrow wasp waists between the thorax and the abdomen.
Life Cycle of the Asian Giant Hornet
In the spring, the queen builds a nest underground in a hollow tree trunk or an empty rodent burrow where she lays her eggs and tends to her female worker offspring. When about 40 of these workers have become adults, they take over the queen’s task of tending to the growing colony and foraging to feed it while the queen continues to lay eggs.
Towards the end of the summer the queen produces male offspring and next year’s queen. The males then leave the nest and wait for the queen to also emerge. After they mate with her, the new queen finds herself a place to overwinter in order to continue the life cycle the following spring.
It is during the late summer and early fall when the Asian giant hornet poses the greatest danger to honeybee colonies. Up to 50 of the workers, in search of food for the new queen and the males, attack a honeybee colony. With their strong mandibles, they tear the honeybees apart, often decapitating them, in order to get to the eggs, larvae, and pupae, which they then feed to their own young.
Do Asian Giant Hornets Attack Humans?
Asian giant hornets only sting when their food source or nest is being threatened. Because of the size of the stinger and the amount of venom it contains, the stings are reported to be extremely painful.
How to Distinguish Asian Giant Hornets from Similar Looking Species
Several other large insects might be mistaken for Asian giant hornets. They can be distinguished either by their much smaller size, or by a different color or pattern.
The European hornet (Vespa crabro) is also a very large hornet, but its face is lighter in the front and darker in the back whereas the head of the Asian giant hornet has the same even yellow color.
Another distinctive feature is the pattern on the abdomen of the European hornet. Just below the thorax, it has dark triangles, and on the lower parts of the abdomen, the dark parts are teardrop-shaped. The stripes of the Asian giant hornet are solid.
The European hornet does not build its nest underground but in hollow spaces of barn walls, attics, and in dead hollow tree trunks.
The bald-faced hornet (Dolichovespula maculata) is not actually a hornet, but instead a yellowjacket wasp. It is much smaller than the Asian giant hornet. Workers are about three quarters of an inch and the queen is about one inch long. The face of the bald-faced hornet is light and not yellow, and it has black markings down the front. Its abdomen is entirely black with only some drops on the lower segments.
The bald-faced hornet builds egg-shaped papery nests high up in the air on tree limbs or the overhangs of buildings.
Yellowjackets, of which there are several species, are much smaller than Asian giant hornets. The workers are about one half inch long, making them about one third of the size of the Asian giant hornet workers. The yellowjacket queens are about half the size of Asian giant hornet workers.
Western and Eastern Cicada Killer Wasp
The females of the western and eastern cicada killer wasp are similar in size to the Asian giant hornet. You can tell the eastern cicada killer wasp apart from the Asian giant hornet by the entirely black end of its abdomen. The thorax of the western cicada killer wasp is reddish, not black like the thorax of the Asian giant hornet.
Both cicada killer wasps are native solitary wasp species. While they also build their nests in the ground, they are not aggressive, but beneficial insects which help reduce cicada populations.
Depending on your location, you might see other insects that appear similar to the Asian giant hornet. To rule out any misidentification, check out this detailed USDA overview of Asian giant hornet lookalikes.