New Invasive Yellow-Legged Hornet Detected In U.S.

An apex predator in the insect world, yellow-legged hornets could threaten honey bees and other native pollinators.

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Last August, a Savannah, GA, beekeeper discovered an unusual-looking hornet outside of his apiary, and reported it to the Georgia Department of Agriculture (GDA). As it turned out, it was an invasive yellow-legged hornet and the first confirmed detection in the U.S. Three months later, South Carolina officials captured their first hornet. So where are we now? Have there been other detections? Are these hornets a threat to pollinators and agriculture? USDA’s National Policy Manager Anne LeBrun answered these questions and others, and provided a snapshot from this developing situation.

“Here’s the latest,” said LeBrun. “GDA found and eradicated 11 nests since their initial detection. This year they’ve set about 1000 survey traps in six counties—most are in Chatham County, GA. As of June 21, they’ve caught more than 40 hornets. It’s a different situation across the Savannah River in Jasper and Beaufort Counties SC. There, South Carolina’s plant industry staff have trapped four hornets, but they haven’t found any nests yet. A Bluffton, SC, resident however found and removed a nest on their house. That nest was sent to USDA’s Pest Identification Technology Laboratory, where it was confirmed as a yellow-legged hornet’s nest.”

The yellow-legged hornet is a social wasp native to Southeast Asia. Its nests look like paper cones with a single entrance, and they hang in trees and on structures such as barns, garages and sheds. This species feed on insects, including honey bees. If they become established in the U.S., they could threaten our domestic and feral honey bees, and other native pollinators. Their presence could also disrupt the pollination of many crops.

USDA has provided the States with money through rapid response funding for survey and eradication activities, and public outreach. USDA’s National Identification Services staff is also testing DNA from yellow-legged specimens to determine where they came from. So far, the testing has not identified a country of origin but likely ruled out ancestry with invasive yellow-legged hornet populations in Europe. Additionally, local staff continue to assist with weekly trap checks.

“These hornets aren’t more aggressive towards people than any of our native hornets; however, they are an apex predator in the insect world. That means they are at the top of a food chain without natural predators, and honey bees are at risk,” LeBrun explained. “Yellow-legged hornets display stalking behaviors around honey bees. They hover outside a honey bee’s hive waiting for foraging bees to return. That’s when they attack and carry off the bees to their own colony to feed their developing brood. This behavior is sometimes called ‘hawking’.”

What To Look For

The yellow-legged hornet can be mistaken for a few domestic species. Take a look below at its distinctive markings. Then review images of the look-alike species side by side with the yellow-legged hornet in the “Yellow-Legged Hornet Look-Alikes” section. These other species are more likely to be found in the U.S. and do not pose a significant environmental or agricultural threat. In fact, some of these look-alikes can be beneficial pollinators.yellow-legged hornet

Body length

  • From 0.7 to 1 inch long

Coloration

  • Head: Mostly black with some front-facing yellow or orange and black eyes
  • Thorax: Mostly solid dark brown or black
  • Abdomen: Alternating bands of dark brown or black and yellow or orange
  • Legs: Brown or black near the body, ending in yellow segments

Yellow-legged hornets have a “wasp waist” between the thorax and abdomen.

Have you seen this pest or signs of pest damage? Immediately report your findings.

Find your State plant regulatory official
Find your State plant health director

In Georgia only, people should report potential sightings of the yellow-legged hornet through the Georgia Department of Agriculture’s online form.

Article and photos from the USDA’s “Plant Protection Today.”

For more on invasive and pest insects, read:

Mosquito Control: Biting Back!

USDA’s Most Recent Plans For Eliminating Asian Longhorned Beetle

Box Tree Moth Quarantine Areas Expanding

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