“Murder Hornets” in SC?

From Clemson Apiculture Specialist Ben Powell.

The story of the introduction of the Asian Giant Hornet (AGH) into North America has been circulating for at least six months by various news sources, but the use of the term “murder hornet” in the NY Times article this past weekend created a viral sensation that is now being run by local news media statewide.

The term “murder hornet” was coined to describe the carnage created when they attack honey bee colonies. The appropriate name is the Asian giant hornet (AGH), Vespa mandarinia.  The AGH was first detected in September of 2019 on Vancouver Island near Nanaimo, Canada.  In December, a dead specimen was found in Blaine, Washington on the Canadian border, and credible attacks on honey bee hives were recorded. At present, AGHs have never been found in South Carolina or the eastern US, and experts say there is no cause for concern in SC.

AGHs are the largest hornet in the world. Though they are frequently confused with European hornets (Vespa crabro), AGHs are nearly twice their size. AGH queens are at least 5 cm (2 inches) long and workers are 3.5 to 4 cm, while the European hornet queens are 3 to 3.5 cm long and workers are 1.8 to 2.5 cm. Other distinguishing features include:

  1. Pronounced genae (cheeks, the region of the head between the frontal suture and the back of the head)
  2. Deeply incised clypeus (facial plate above the upper lip)
  3. Mesonotum (back between front wings) is entirely dark
    • European hornet has pair of longitudinal yellow patches on mesonotum
AGH vs EH.jpg

Comparison of distinguishing features of Asian giant hornets (left) versus the European hornet (right). Image credit: Allan Smith-Pardo, Invasive Hornets, USDA APHIS PPQ, Bugwood.org 
Edited by Ben Powell, Clemson University

The AGH is native to eastern Asia, ranging from India through China to Korea and Japan. Genetic analysis of recovered specimens suggests North American populations may have multiple origins (one from Japan and another from Korea), suggesting two separate introductions.

Adult hornets feed on sweet substances and have a high affinity for honey bee colonies, as they contain both sweet fluids for adult workers and larval insects which they feed to their young. AGHs are about five times larger than a honey bee and easily overcome their defenses. Honey bees might be able to fend off a single hornet by balling around it, but when multiple AGHs attack, they decapitate the defending honey bee workers, leaving behind bee carcasses at the hive entrance and bottom board. After destroying the workers, the hornets then collect the larvae. This destruction of the colony can occur in just a few hours.

AGHs are no more harmful to people than wasps like European hornets, bald-faced hornets, yellow jackets, or paper wasps.  They are no more defensive than other wasps and stings tend to produce similar reactions, including localized pain and swelling with some isolated tissue necrosis. Deaths associated with AGH have mostly been people suffering from anaphylaxis or other underlying health issues.

For more information, see the following resources: