A few years ago, Americans were warned about “Asian Giant Hornets” – aka “murder hornets” – that were spotted in Washington state. While that menace seems to be under control for now, a new Asian hornet species known for its penchant for murdering honeybees has snuck into the US. The “Yellow-Legged hornet” feeds on a variety of other native pollinator insects as well and it’s feared their presence could disrupt the pollination of many crops.
The yellow-legged hornet (Vespa velutina) is a social wasp species that is native to Southeast Asia. This wasp was first found in the US in Savanah, Georgia by a beekeeper. On August 9, 2023, APHIS confirmed it as a yellow-legged hornet. In November 2023, YLH was reported in Jasper County, South Carolina, though no nests have been found. As far as I can determine, these are the only two states that YLH has been found so far.
The adult hornets are a little less than an inch long. The species has distinctive yellow tarsi (legs) but the colors of their thorax can vary from a velvety brown to black with a brown abdomen. Each abdominal segment has a narrow posterior yellow border, except for the fourth segment, which is orange. The head is black and the face yellow.
Yellow-legged hornets construct nests above ground made from paper-like materials. These nests can be found hanging in trees and bushes, and on structures such as barns, garages, and sheds. The nests usually start low to the ground before moving to a secondary nest higher off the ground once the colony has grown enough.
One Asian hornet can hunt and consume up to 50 bees in a day, but their collective impact is where the real concern stems from. Nests are unusually large, and as the colony grows, they can house up to 5,000 – 6,000 workers on average. A French study found that a single Asian hornet nest consumes nearly 25 pounds of insects each summer. YLH will hunt foraging honey bee adults and invade honey bee colonies to steal the larvae. While YLH prefer honeybees, they will eat a number of flying insect species and even dead animals.
YLH was first found in Europe 2004 and has since spread unchecked as far north as Ireland as of 2021. According to experts, the entire range of YLH in Europe converged to a single mated queen arriving from China some 20 years ago. It’s estimated that France now has some 500,000 nests. In Britain, YLH have been observed hovering outside beehives and picking off worker bees as they emerge. It can also decimate colonies through intimidation by deterring honeybees from foraging.
French beekeepers attribute 29% of honeybee colony mortality to the hornets. In Portugal, beekeepers in some regions claim 50% of their hives have been lost because of YLH. In continental Europe, ripening fruit in vineyards and orchards has been plundered by Asian hornets, posing a threat to wine and fruit production. In France, some outdoor markets have had to move indoors because the hornets are attracted to the fresh fruit, fish, and meat. YLH has also invaded South Korea, Japan, and the Middle East.
YLH is a menace to the public, as well. Reiner Jahn, a hornet-buster and research assistant for a local landscape conservation association in Germany, describes the pain of a yellow-legged hornet sting as “digging a hot rusty knife into your flesh.” They are also aggressively defensive of their nests.
Experts in the US have conflicting opinions on whether YLH could establish itself in the states. UC Davis distinguished professor Lynn Kimsey, director of the Bohart Museum of Entomology, said she thinks it’s unlikely since YLH is also native to regions with wet summers. However, she notes that “anything is possible” and warns it could have a “potentially huge” impact on honeybee colonies.
In its native range, the hornet mainly hunts the Eastern honey bee. Bees there suffocate the hornet by balling it. In the US and Europe, however, it has no natural predators. The Georgia Department of Agriculture asks that if you come across a nest and/or queen, please take a photo and report it using the online yellow-legged hornet reporting form or send them an email. Learn more HERE. For others, contact your state’s Department of Agriculture, Department of Natural Resources, U.S. Fish and Wildlife Service (USFWS), or other relevant organization. (Sources: Georgia Department of Agriculture, Smithsonian, UGA Bee Program, Clemson News)
