Get to know these Asian 'murder hornets'
The Asian giant hornet (Vespa mandarinia) or sparrow wasp is a species of wasp native to parts of Japan, China, India and Sri Lanka.
Touted as “murder hornets” in the national headlines, their presence is causing widespread concern.
A nest of these insects was discovered and destroyed in Vancouver Island, Canada, in September 2019, and in December a dead specimen was found in the state of Washington.
Pennsylvania gardeners have no reason to panic, as there are no reports of the Asian giant hornet in our state. It is unlikely that they will arrive in the near future.
However, these insects are of interest because the Asian giant hornet happens to resemble and can be confused with two other species of large wasps native to Pennsylvania: the European hornet (Vespa crabro) and the Eastern cicada killer (Sphecius speciosus).
Asian giant hornets are some of the largest wasps in the world, with the workers averaging 1.5 inches in length. Their queen reaches two inches in length with a wingspan of three inches. Their distinctive yellow orange head with their yellow and black-striped abdomen gives them a Halloween-themed look.
The label “murder hornet” given to these insects is a misnomer. Like any social wasp, the Asian giant hornets will defend themselves along with their nests if threatened, but they are not human-seeking and it is not clear that their sting is any more harsh than other bees or wasps.There is great concern, however, about the potential impact of the Asian giant hornet on the honeybee population. Like other social wasps, these hornets are predators of other insects.Under normal circumstances, Asian giant hornets are solitary. For an unknown reason, in the late fall, the Asian giant hornets become more aggressive, banding together to conduct a mass attack on honeybee nests.This “slaughter phase” continues until the colony of adult honeybees decreases. After decapitating the adult honeybees, the hornets feed the honeybees' abdomens to their young.In the following “occupation phase,” the hornets enter the bee hive and gather the protein-rich larvae and pupa to feed their own larvae. It is not likely that a single hornet will destroy a honeybee colony.Japanese honeybees (Apis cerana japonica), have co-evolved with the Asian giant hornet and have developed a unique defense against them. Up to 400 worker bees form a tight ball around the attacking hornet and buzz with their wings, raising the temperature to a level of 122 degrees Fahrenheit, thus killing the wasp.Our European honeybee (Apis mellifera), unfortunately, has no defense against this predator and the concern is that, should the Asian giant hornet become established in North America, their presence may have a negative impact on honeybees and American beekeepers.Overall, there is no reason to be alarmed about the Asian giant hornet. Aside from the two isolated reports from Washington State and Vancouver Island, there are no known accounts of these wasps in North America.Current efforts are being taken to detect, monitor, and control the hornets and to determine if they have become established in any areas.Visit the Penn State Extension at https://extension.psu.edu/asian-giant-hornets to learn more about the life cycle of the Asian giant hornet.If you have questions about the Asian giant hornet, call the Master Gardener Garden Hotline at 724-287-4761, Ext. 7, or email the Master Gardeners at butlermg@psu.edu.Expert Master Gardeners and Extension Educators from across the state will be answering some questions during our new program, “Garden Hotline LIVE.” Submit questions for the live show here: pennstate.qualtrics.com/jfe/form/SV_6fbKDzHz5bNgknj.For more information about how to watch Garden Hotline LIVE, visit our statewide Penn State Extension Master Gardener group page: https://www.facebook.com/groups/696217890434068.Mary Reefer is a Penn State Extension Master Gardener of Butler County.
