A simple tubular trap placed in front of honey bee hives cut yellow-legged hornet attacks by about fivefold in Spanish field tests, helping bees forage normally while capturing the invasive predator and limiting impact on nontarget species. Shown here, the trap tested by researchers in a new study is a modified version of a trap designed by Spanish beekeeper Koldo Belaska. It features a horizontal mesh tube that is placed in front of entranceways to hives, with vertical “chimney” tubes at each end for trapping hornets. (Photo originally published in Bas et al. 2026, Journal of Economic Entomology)

By John P. Roche, Ph.D.

Núria Roura-Pascual, Ph.D.

Josep M. Bas, Ph.D.

Yellow-legged hornets (Vespa velutina) are an invasive species in Europe, Japan, and South America and have been discovered recently in the southeastern U.S. These pests disrupt honey bee (Apis mellifera) colonies by preying on adult and larval honey bees and blocking bees from leaving nests, disrupting honey and pollen production. This disruption is particularly concerning given that pollinators are declining globally.

To develop a method for protecting honey bee hives from yellow-legged hornets, a group of researchers in Spain tested a tubular hornet trap that can be placed in front of honey bee hives. Their study was published in May in the Journal of Economic Entomology.

Yellow-legged hornets arrived in France in 2004 and are now present in numerous countries in Europe. They spread easily because they have a high reproductive rate and because their founding queens have high dispersal capabilities. Control measures for yellow-legged hornets include destroying nests or trapping individual hornets. Koldo Belaska, a beekeeper in Spain, developed a trap with a horizontal mesh tube that is placed in front of entranceways to hives, with vertical “chimney” tubes at each end for trapping hornets:

The new study was led by Josep M. Bas, Ph.D., professor in the Department of Environmental Sciences at the University of Girona in Catalonia, Spain. He was joined by Girona colleagues Quim Canelles, Ph.D., and Núria Roura-Pascual, Ph.D., and Jordi Artola of the Dorcus Invertebrate Observatory in Catalonia.

Bas and colleagues modified the Koldo Belaska trap by increasing the mesh-size openings from 6 millimeters to 8 millimeters (mm), and placing traps about 8 centimeters (cm) in front of the entrances to hives. They then tested the modified trap’s effectiveness in capturing yellow-legged hornets. Their study examined how many hornets are caught in the modified Koldo Belaska trap, changes over time in the size or the castes of hornets captured, and whether the modified Koldo Belaska traps avoid capturing nontarget species.

Yellow-legged hornets (Vespa velutina) are an invasive species in Europe, Japan, and South America and have been discovered recently in the southeastern U.S. They disrupt honey bee colonies by preying on adult and larval honey bees and blocking bees from leaving nests, disrupting honey and pollen production. (Photo by Oriol Sastre via iNaturalist, CC BY 4.0)

Traps were one-meter perimeter tubes of galvanized wire mesh. The team placed 25-by-15 cm rectangular windows along the bottom of the mesh tube to allow hornets to enter the trap. They attached chimneys of mesh to each end of the trap, and each chimney had a hornet collection chamber attached to the top so that hornets could not leave.

In 2023, they installed the modified traps in 12 apiaries in three localities in the Girona area of Catalonia. The apiaries ranged in size from two to forty-one hives. They installed traps at most of the apiaries in early July, but they installed traps at two of the apiaries in August. They reported yellow-legged hornet captures as captures per day per hive.

They found a lot of variability in capture rates among apiaries. Smaller apiaries tended to suffer greater hornet pressure than larger apiaries, and the smallest apiary averaged 11 captures of hornets per day. Bas and colleagues observed different temporal patterns in different regions. Some regions showed bimodal patterns where captures began early in the season, then declined, then increased again. Apiaries in the Garrotxa and Selva regions, however, tended to show unimodal patterns where captures began late in the season. The researchers suggest that these variations probably result from environmental differences among the regions. In general, they found that modified Koldo Belaska traps reduced the number of hornets by about five times.

A simple tubular trap placed in front of honey bee hives cut yellow-legged hornet attacks by about fivefold in Spanish field tests, helping bees forage normally while capturing the invasive predator and limiting impact on nontarget species. Shown here installed on hives in an apiary, the trap tested by researchers in a new study is a modified version of a trap designed by Spanish beekeeper Koldo Belaska. It features a horizontal mesh tube that is placed in front of entranceways to hives, with vertical “chimney” tubes at each end for trapping hornets. (Photo courtesy of Josep M. Bas, Ph.D.)

A simple tubular trap placed in front of honey bee hives cut yellow-legged hornet attacks by about fivefold in Spanish field tests, helping bees forage normally while capturing the invasive predator and limiting impact on nontarget species. Shown here installed on hives in an apiary, the trap tested by researchers in a new study is a modified version of a trap designed by Spanish beekeeper Koldo Belaska. It features a horizontal mesh tube that is placed in front of entranceways to hives, with vertical “chimney” tubes at each end for trapping hornets. (Photo courtesy of Josep M. Bas, Ph.D.)

In 2022, they measured the size of yellow-legged hornet individuals captured at one of the apiaries to examine the composition of hornet castes. Individuals were frozen and later examined morphologically, and their caste was determined by external morphology. They found that over 97% of hornets captured were yellow-legged hornets. They caught 7,554 yellow-legged hornets. Over 94% of these were workers, while about 5% were founding queens, and fewer than 1% were males.

They examined the degree to which nontarget species were captured in the traps at seven apiaries in the Garrotxa region in 2023. Over 90% of the captures were yellow-legged hornets. About 48% of nontarget captures were European hornets (Vespa crabro).

In conclusion, Bas and colleagues write, “Overall, the modified KBA trap not only yielded a high number of hornets captures but also strategically promoted spatial separation between hornets and hive entrances, thereby reducing colony disturbance and enabling uninterrupted foraging activity.”

The modified Koldo Belaska traps reduced yellow-legged hornet predation on hives by about five times, which is an impressive control outcome. And the traps were able to do this while preserving the normal foraging activity of the bee hives. And, as the authors observe, “Preserving normal colony activity while effectively reducing hornet populations is critical for maintaining apiary productivity and ecological balance.”

Looking ahead, Bas and colleagues suggest that future research on yellow-legged hornet traps could refine designs to improve selectivity to avoid nontarget species and adjust deployment methods to optimize trapping in different environments or with different life cycles of target and nontarget insects.

John P. Roche, Ph.D., is an author, biologist, and scientific writer with a Ph.D. and postdoctoral fellowship in the biological sciences and a dedication to creating compelling stories for readers. He authors books and writes materials for universities, scientific societies, and publishers. Professional experience includes serving as a scientist and scientific writer at Indiana University, Boston College, and the UMass Chan Medical School; and as editor of science periodicals at Indiana University and Boston College.