Are Asian Giant Hornets a Threat in Texas?

By Dr. David Ragsdale Texas A&M Agrilife     

The Asian giant hornet, Vespa mandarinia, or AGH, is a large, predaceous hornet native to Asia, most commonly found in Japan and South Korea.     

The AGH is the world’s largest hornet, slightly larger than the cicada killer wasp common in Texas. It was discovered for the first time in North America in August 2019 in British Columbia, Canada, and was located and eradicated in September 2019.     Two specimens were also collected near Blaine, Washington, in the northwest corner of the state. Efforts are underway this spring to trap hornets near Blaine and other sites where citizens have seen or collected hornets.     

Until insects are trapped in the spring and summer of 2020, we won’t know if this species has adapted to the Pacific Northwest climate.     

Asian giant hornets have not been detected in Texas.    

What threat does this hornet pose?     

The most immediate threat is to the beekeeping industry. This insect is a specialized predator of honey bees in Asia. Because the Japanese honey bee co-evolved with the AGH, it has defensive behaviors that protect it from attack. However, the Japanese honey bee is not the same species used in the U.S. The European honey bee, the species used in the U.S., has no defense against the AGH. In a matter of hours, 15 to 30 AGH can kill a hive of honey bees containing 30,000 to 50,000 workers. The hornets then occupy the hive, kill the developing larvae and take this protein-rich meal to their nest.     

In addition to the threat to bees and beekeepers, this large venomous insect (1.5 to 2 inches in length – or the size of your thumb) can deliver a powerful sting. Its venom is no more toxic than that of other stinging insects, but in Japan, the AGH kills 30 to 50 people a year.     

The AGH is a predator of honey bees. If established, this hornet could devastate honey bee populations. Honey bees are managed for both their honey and their pollination services.     T

he AGH will aggressively defend its nest or any honey bee hive it occupies. Migratory beekeepers who move bees between Texas and the Western U.S. are not how the AGH would make it to Texas.     

Any honey bee hive occupied by AGH would be occupied by sterile workers, which cannot reproduce and begin a new colony. Management and biology     

Our first line of defense are the many commercial and hobby beekeepers in the state of Texas. If they notice bee kills and observe these insects near a hive, they should contact the Texas Apiary Inspection Service for assistance.     

Asian giant hornets do not construct an aerial nest. Instead, like many other hornets and yellow jackets, these hornets use an abandoned animal burrow to build their nest. This makes locating a nest very difficult. But locating and eradicating the Asian giant hornet nest in spring and summer is the goal.     

In fall, the nest begins to develop reproductives (males and virgin queens) that leave the nest. Only the mated queen overwinters. All other nest occupants die during the winter. The newly mated queen seeks shelter where she will pass the winter, emerging in spring to find a suitable nesting site to rear the initial set of sterile workers. Once the nest has a few dozen workers, the queen never leaves the nest again and the cycle starts over in the spring. Movement     

The AGH is a strong flier and can travel several miles. When a honey bee colony is attacked, an AGH colony is likely within 0.5 to 1.5 miles. A related hornet from Asia recently established in France and its rate of spread is about 60 miles per year. Since this range is beyond the flight distance of this species, human-aided movement is likely. Shipping containers are suspected as a key route of entry into North America. Another possible route of entry is by air transport.     

Early detection followed by eradication of nests before fall is critical to prevent establishment.