Pest alert! Invasive yellow-legged hornet threatens honey bees

A worrying discovery has been made in Savannah, Georgia, where a hornet, known as Vespa velutina , was officially identified by the Georgia Department of Agriculture in 2023.

A beekeeper in the area first found it. Although different from the "murder hornet" ( Vespa mandarinia ), which was first confirmed in Vancouver and nearby areas of Washington state, both types of hornets are dangerous to honey bee larvae and adults. The finding of Vespa velutina has led to efforts to stop it from spreading to Florida and the rest of the United States.

Vespa velutina , an invasive species from Southeast Asia that first showed up in Europe in 2004, is a general predator, but it mainly targets honey bees, which has caused a lot of concern in the beekeeping industry.

Approximately the size of a nickel, Vespa velutina features distinctive black and yellow coloring with yellow/white legs, earning it the nickname "yellow-legged hornet."

The life cycle of Vespa velutina starts with a single queen building a nest, laying eggs, and waiting for workers to hatch. Nests can be found in various locations and can grow to have around 6,000 hornets. The hornets hunt honey bee colonies more during the summer, and they mate later in the year. The life cycle ends with the death of all workers and males, and new nests are built the following year.

Remarkably, a single mated female has the potential to start a new colony on her own. Primary nests, starting as small as a tennis ball, undergo significant growth. The secondary nests can be as tall as 3.3 feet and have more than 17,000 cells.

These nests are usually found 60 to 70 feet high, making them hard to reach. A single hornet nest can eat up to 25 pounds of insects in one season, showing how much of an impact Vespa velutina colonies can have on the environment.

Vespa velutina is a predatory wasp that eats different types of arthropods and even feeds on decaying animals when given the chance. Although the full ecological impact isn't clear, DNA found in their stomachs shows that they eat other wasps, bees, butterflies, moths, and spiders.

However, honey bees, especially Apis mellifera , are their favorite targets, posing a significant threat to beekeepers. In Europe, reports suggest that up to 30% of honey bee hives are weakened by these wasps, and about 5% are completely destroyed.

Initially attracted to the honey bee hive by hive pheromones, yellow-legged hornets position themselves away from hive entrances, waiting for returning foragers, resulting in a "carpeting" of workers at the entrance. This term refers to the clustering or accumulation of honey bee workers near the hive entrance as they attempt to defend against the invading hornets. This behavior unfortunately leads to decreased colony production.

In response to this discovery, the UF/IFAS Honey Bee Research and Extension Laboratory is working with the Florida Department of Agriculture and Consumer Services (FDACS) to share information and quickly handle reports of hornet sightings.

It's important to know that there are many native species in the United States that look similar to the invasive hornet but aren't a threat to honey bees. In fact, many of them are valuable pollinators. You can find a photo gallery of these lookalikes by visiting aphis.usda.gov and searching for 'yellow-legged hornet.'

While Vespa velutina can easily be confused with other hornets that are not problematic to honey bees, residents who believe they have identified Vespa velutina are encouraged to call the FDACS hotline at 1-888-397-1517. If you can catch a sample or take a clear photo of the hornet, email it with the location details to dpihelpline@fdacs.gov . This helps with monitoring efforts.

Public awareness and teamwork are essential to reduce the impact of Vespa velutina on honey bee populations in Florida and beyond. For more information about the yellow-legged hornet, check out the Vespa velutina UF/IFAS Featured Creatures fact sheet.

Molly Jameson is the Sustainable Agriculture and Community Food Systems Extension Agent with UF/IFAS Extension Leon County, an Equal Opportunity Institution. For gardening questions, email the extension office at AskAMasterGardener@ifas.ufl.edu

This article originally appeared on Tallahassee Democrat: Pest alert! Invasive yellow-legged hornet threatens honey bees