Yellow-Legged Hornet

In August 2023, the Georgia Department of Agriculture (GDA), in coordination with the United States Department of Agriculture Plant & Animal Health Inspection Service (USDA APHIS) and the University of Georgia, confirmed the presence of a yellow-legged hornet (YLH; Vespa velutina) near Savannah, Ga. This is the first time a live specimen of this species has been detected in the open United States.

Report a sighting

On this page you'll find:

• Extension County Agent Resources
• Beekeeper Resources
• Yellow-legged hornet images

Side-by-side comparisons of the yellow-legged hornet (Vespa velutina) to the European hornet (Vespa crabro) and Eastern cicada killer wasp (Sphecius speciosus) (USDA photos by Hanna Royals):

Extension County Agent Resources

Yellow-legged hornet, Vespa velutina

Keith Delaplane, William Hudson, Allison Johnson

Department of Entomology, University of Georgia

On Tuesday, August 15, 2023, Georgia Commissioner of Agriculture Tyler Harper announced the first detection of the yellow-legged hornet (YLH), Vespa velutina, in North America. This factsheet will give you the basic discussion points.

1. The specimen was reported by a beekeeper on August 9th from near the port of Savannah.
2. This hornet is not to be confused with the Asian (now “Northern”) giant hornet discovered in the Northwestern USA in 2020 and which has so far not been found outside that region.
3. Like all stinging wasps and bees, YLH poses a sting risk to persons and pets, especially for persons who suffer from allergic anaphylaxis. Even so, in Hubei Province, China where YLH is native, "all wasps" were responsible for only 54 human deaths in two years.¹ The U.S. averages 72 deaths per year from all stinging insects.² This is not a major health threat to Georgians.
4. YLH is primarily a threat to Georgia’s beekeeping industry. The hornet is a voracious predator of honey bees. Even if it fails to kill a colony, its threatening behavior at hive entrances can intimidate bees from foraging and cause the colony to decline.
5. Georgia consistently ranks within the top 20 states for honey production and the top 2-3 for the production of package bees and queens.
6. The annual contribution of honey bees and other biotic pollinators to Georgia’s agricultural economy is over $480 million.³
7. UGA scientists and GDA are consulting with colleagues in Washington state and Europe to draw on their experience and formulate a plan for eradication, surveillance and management.
8. YLH has been present in Western Europe since 2004. UGA scientists are cooperating with colleagues in Europe to fast-track a response for Georgia.
9. As information becomes available, Georgians will have the chance to report suspect specimens to websites maintained by GDA and the Center for Invasive Species and Ecosystem Health at UGA Tifton Campus.
10. The accompanying graphic shows key diagnostic characters for the yellow-legged hornet and some native lookalikes.
11. Beekeeper-oriented information is available below.

Sources

1 Xie C, Xu S, Ding F, et al. PLoS One. 2013;8:e83164

2 National Center for Health Statistics, National Vital Statistics System, Mortality Data, 2011–2021. https://wonder.cdc.gov/Deaths-by-Underlying-Cause.html

3 Pless et al. 2021. J. Agric. Appl. Econ. 53: 322

Download the 2023 yellow-legged hornet factsheet

Below is a graphic with pictures of the yellow-legged hornet and some lookalike species found in Georgia. 

Four identifying characteristics of the yellow-legged hornet (YLH):

1. Size: Adults are about 2 cm long. See comparisons to lookalike species in Georgia.
2. Narrow waist: Look for a narrow waist, more cinched than the sawfly lookalike.
3. Yellow fourth abdominal segment: Look for a strong yellow stripe on the fourth abdominal segment shown on the diagram below with an arrow.
4. Yellow legs (bottom half): The namesake characteristic of the YLH is the yellow color found on the bottom half of the insect's legs.

Beekeeper Resources

A Georgia Beekeeper’s Guide to the Yellow-legged hornet, Vespa velutina

Keith Delaplane, Jennifer Berry

Department of Entomology, University of Georgia

An unusual-looking hornet was found in a beekeeper’s apiary near the port of Savannah in July 2023 and by August 9 confirmed by USDA APHIS as the yellow-legged hornet (YLH), Vespa velutina. This invader is a serious predator of honey bees.

There is potential for confusion with other names. YLH is called the “Asian hornet” in Europe. A related species, the giant northern hornet (formerly “Giant Asian hornet”) Vespa mandarinia, was detected in Washington state in 2020. To be clear, V. velutina is not the giant northern hornet that has so far not been found outside the Pacific Northwest. Both hornets, however, are serious predators of honey bees.

The YLH has been moved outside its native southeast Asia by inadvertent human traffic. Today it is found as far north as Finland and England and throughout much of western Europe where it was first detected in France in 2004. In France, the invasion front appears to be more rapid in regions receiving comparatively higher precipitation during the driest months of the year (Villemant et al., 2011). In Georgia, genetic tests are underway to determine if the V. velutina specimen found in Georgia came from Europe or directly from Asia.

In its native range, YLH is a natural predator of the eastern honey bee Apis cerana which has evolved defensive behaviors against the hornet, including an example of social fever. A hornet that enters a hive of A. cerana is enveloped in a ball of defensive bees who raise their body temperatures to near-lethal limits that effectively cook the invading hornet but spare the bees. The western honey bee Apis mellifera, used for beekeeping everywhere including Georgia, can express reduced forms of social fever, but never enough to kill a hornet. Western honey bees are essentially defenseless against YLH.

Biology

The life cycle of V. velutina is typical for most wasp species. Mated females overwinter in solitude in some protective cover. In spring, the female emerges and makes a paper nest of cells constructed from macerated wood pulp. In these paper combs of cells, the female lays her first eggs and personally forages, feeds the brood, and defends the nest until a sufficient number of daughter workers emerge who take over colony work, freeing their mother to concentrate on egg laying. Often the initial nest is constructed near ground level, but a mature colony may relocate into the upper reaches of a tree. Their arboreal nests assume the “egg-shaped paper basket” appearance similar to nests of the naturalized European hornet, Vespa crabro (Feás Sánchez and Charles, 2019). By late summer the colony’s population peaks and the colony switches efforts from growth to producing fertile females and males after which the colony begins a slow decline. Eventually, all members die except for the newly-mated females who overwinter and resume the cycle next spring.

Depredations to bees

The chief food of adult wasps is carbohydrates such as flower nectar, ripening fruit, or tree sap. The brood requires animal proteins, typically from other arthropods, carrion, or human food scraps. In one study, Apidae (the insect family including honey bees) comprised one-third to two-thirds of V. velutina larval dietary protein. Adults macerate prey into flesh pellets which they feed individual larvae (Turchi and Derijard, 2018). 

Honey bee colonies constitute concentrated sources of readily-available food. Typically, one or more hornets begin preying upon honey bees where they find them most concentrated - at hive entrances. Hornets snatch bees from mid-air or from hive landing boards. As more hornets discover the bee hive the attack intensifies until it is nearly relentless. In this manner, a relatively small number of hornets can depopulate an apiary within days. Even if hornet numbers are small, their presence can intimidate honey bees from foraging and induce a slow decline in colony strength. The foraging range of one V. velutina colony can be up to 1000 meters, a benchmark that defines the radius within which a beekeeper could search for a problem hornet nest (Poidatz et al., 2018). Hornet depredation begins in early summer and increases steadily until autumn, dropping off only after hornet colonies die out.

Protective clothing

Ordinary beekeeping suits will not provide the necessary protection against these hornets. Beekeepers in the UK recommend suits made of double-walled mesh fabric with a 5 mm gap. The extra space provides more distance between the user’s skin and penetrating stingers. High-top boots and extra-thick gloves are also essential. Ordinary beekeeping veils are suitable as long as the mesh doesn’t touch the user’s skin.

Management tools

Beekeepers, regulators and scientists in Europe have focused on a variety of physical and biological control methods, as reviewed by Turchi and Derijard (2018) in their open-source article available by searching their title. Unfortunately, none of these practices has halted or reversed the slow progression of the hornet across France, northern Spain, and Portugal. Some of the more practical control methods are summarized here.

Modified hive entrances

Sometimes called “bee hive muzzles,” these devices are designed to permit bee traffic but confuse and exclude hornets. At best, the devices prevent hornets from directly entering bee hives but in the end, they simply push the predation perimeter further away.

Badminton rackets

As desperate as it sounds, killing hornets with a badminton racket one at a time may be the most practical and effective control method for hobby beekeepers. 

Homemade and manufactured traps

There are two approaches to trapping – trapping early-nesting queens to reduce season-long hornet nest density, and trapping foraging workers during hunting season. In most cases the trap includes a bait solution that is either proprietary or a home-made mixture of beer, white wine and berry syrups that are supposed to attract hornets and repel bees.

One homemade trap design uses a common liter soda bottle. The top one-third of the bottle is cut off, reversed, and its narrow end is pressed and glued into the bottom end, creating a funnel. The bait solution is poured into the halfway mark, and the traps are suspended in the apiary. Drowned hornets may serve as additional attractant to more hornets.

A few European companies have made devices for trapping YLH with or without proprietary baits. These include electric traps and one-way tunnel traps advertised to be highly specific for V. velutina.

The performance of these traps is generally disappointing. In one comparative study of trap designs, V. velutina comprised 3.65% of trap catch in spring and 1.35% in autumn, the rest constituting environmentally irresponsible bycatch (Lioy et al., 2020). Although sex pheromone components have been identified for V. velutina (Cheng et al., 2022), to our knowledge none has been formulated into an effective trap lure.

Locating and removing nests

The most direct management methods involve locating and eliminating nearby hornet nests. Feeding stations are set up in an apiary with protein baits such as chicken or tuna. Anecdotal reports from Korea indicate that fish is a preferred bait. Observers note the arrival of a hornet, visually identify it and follow its trajectory as it returns toward its nest. The bait station is moved to the point of last visual contact, and the process repeated. The search typically ends when a homeward-bound hornet is seen flying upward into a tree canopy where their aerial nests are located. It may help to visualize the insect by dusting it with flour while it is at the feeding station. Researchers in Europe have developed radio-tracking methods to improve the speed and efficiency of finding nests which can be hidden and hard to reach (Kennedy et al., 2018). The insects are attracted to feeding stations of meat, captured, and tiny radio transmitters glued onto their backs after which they are released. Once spotted, the nest is destroyed by a removal specialist who nets the nest, agitates the bag to net the workers who fly out, and physically cuts away the nest, combs and all. The brood and adults are killed by freezing, fumigation, or an approved insecticide.

References

CHENG, Y.-N., WEN, P., TAN, K. & DARROUZET, E. 2022. Designing a sex pheromone blend for attracting the yellow-legged hornet (Vespa velutina), a pest in its native and invasive ranges worldwide. Entomologia Generalis.

FEÁS SÁNCHEZ, X. & CHARLES, R. J. 2019. Notes on the nest architecture and colony composition in winter of the yellow-legged Asian hornet, Vespa velutina Lepeletier 1836 (Hym.: Vespidae), in its introduced habitat in Galicia (NW Spain). Insects, 10, 237.

KENNEDY, P. J., FORD, S. M., POIDATZ, J., THIÉRY, D. & OSBORNE, J. L. 2018. Searching for nests of the invasive Asian hornet (Vespa velutina) using radio-telemetry. Communications Biology, 1, 88.

LIOY, S., LAURINO, D., CAPELLO, M., ROMANO, A., MANINO, A. & PORPORATO, M. 2020. Effectiveness and selectiveness of traps and baits for catching the invasive hornet Vespa velutina. Insects, 11, 706.

POIDATZ, J., MONCEAU, K., BONNARD, O. & THIÉRY, D. 2018. Activity rhythm and action range of workers of the invasive hornet predator of honeybees Vespa velutina, measured by radio frequency identification tags. Ecology and Evolution, 8, 7588-7598.

TURCHI, L. & DERIJARD, B. 2018. Options for the biological and physical control of Vespa velutina nigrithorax (Hym.: Vespidae) in Europe: A review. Journal of Applied Entomology, 142, 553-562.

VILLEMANT, C., BARBET-MASSIN, M., PERRARD, A., MULLER, F., GARGOMINY, O., JIGUET, F. & ROME, Q. 2011. Predicting the invasion risk by the alien bee-hawking Yellow-legged hornet Vespa velutina nigrithorax across Europe and other continents with niche models. Biological Conservation, 144, 2142-2150.

Yellow-legged hornet images

View more images on the hornet screening tool database.