In 2019, the internet collectively lost its mind over the "murder hornet." But the Japanese giant hornet (Vespa mandarinia) — now formally called the northern giant hornet — had been terrorizing beekeepers and killing dozens of people in Asia for centuries before it made headlines in North America. At up to 2 inches long with a stinger that can punch through standard beekeeping gloves, it is the largest hornet on earth and one of the most formidable insects alive.
Size and Appearance
Queens reach 50mm (2 inches) in body length with a wingspan of 76mm (3 inches). Workers average 35–45mm. For comparison, the largest wasp native to Arizona — the tarantula hawk — reaches about 50mm, but is far more slender. The giant hornet is massively built, with a broad orange-yellow head, large compound eyes, and a distinctive banded abdomen of orange and black.
The stinger measures 6mm (1/4 inch) — long enough to penetrate standard beekeeping gloves and inject a substantial dose of venom. Unlike honeybees, hornets can sting repeatedly without dying.
The Massacre: How Giant Hornets Hunt Honeybee Colonies
The giant hornet's most spectacular — and terrifying — behavior is its assault on honeybee colonies. A single scout hornet locates a hive and marks it with a pheromone. Within hours, a raiding party of 20–30 hornets arrives. What follows is a slaughter.
The hornets use their powerful mandibles — not their stingers — to decapitate bees at a rate of one every few seconds. A group of 30 hornets can kill 30,000 honeybees in under 3 hours, leaving a pile of headless bee bodies at the hive entrance. The hornets then occupy the hive, feeding on the honey and carrying bee larvae back to their own nest to feed their young.
European honeybees (Apis mellifera), which have no evolutionary history with giant hornets, are defenseless against this attack. Japanese honeybees (Apis cerana japonica), however, have developed a remarkable counter-strategy.
The Heat Ball: Nature's Most Remarkable Defense
When a scout giant hornet enters a Japanese honeybee hive, hundreds of bees immediately mob it. They form a tight, vibrating ball around the intruder — sometimes 500 bees deep. The bees rapidly vibrate their flight muscles, generating metabolic heat. The ball's internal temperature rises to 47°C (117°F).
The giant hornet dies. The bees survive — their thermal tolerance is 48–50°C, just above the lethal threshold for the hornet. This co-evolutionary arms race has been running for millions of years. European honeybees, introduced to Japan only in the 19th century, have no such defense and are annihilated.
The Venom: Cytotoxic and Neurotoxic
Giant hornet venom contains a complex cocktail including mandaratoxin (a neurotoxin), phospholipase A2 (which destroys cell membranes), and acetylcholine (which causes intense pain). The venom is cytotoxic — it directly destroys tissue — and can cause kidney failure in large doses.
In Japan, giant hornets kill approximately 30–50 people per year — more than any other animal in the country. Most deaths result from anaphylactic shock in people with allergies, but even non-allergic individuals can die from multiple stings due to direct venom toxicity and organ damage.
The hornets are most aggressive in late summer and fall when colonies are at peak size and workers are defending the nest and foraging intensively for protein to feed developing queens.
The US Invasion — and Eradication
In 2019, giant hornets were detected in Whatcom County, Washington State, and in British Columbia, Canada — the first confirmed sightings in North America. The source of introduction is unknown but likely involved accidental transport in international cargo.
USDA APHIS and Washington State Department of Agriculture launched an intensive eradication campaign. Using radio-tagged hornets to locate nests, teams destroyed confirmed colonies in 2020 and 2021. As of 2024, no confirmed detections have been made in the US, and the eradication effort is considered successful — though monitoring continues.
They are not present in Arizona. The Sonoran Desert's dry heat is incompatible with the temperate forest habitat giant hornets require.
Frequently Asked Questions
How big is a Japanese giant hornet?
Queens can reach 50mm (2 inches) in length with a wingspan of 76mm (3 inches). Workers average 35–45mm. The stinger alone measures 6mm (1/4 inch) — long enough to penetrate standard beekeeping gloves.
Are Japanese giant hornets in the United States?
The northern giant hornet was detected in Washington State and British Columbia in 2019–2021. Eradication efforts successfully eliminated known nests. As of 2024, no confirmed detections have been made in the US. They are not present in Arizona.
How many people do Japanese giant hornets kill per year?
In Japan, giant hornets kill approximately 30–50 people per year — more than any other animal in the country. Most deaths are caused by anaphylactic shock, though the venom is also cytotoxic and can cause organ damage in large doses.
How do Japanese honeybees defend against giant hornets?
Japanese honeybees mob scout hornets and form a tight ball, vibrating their flight muscles to raise the temperature to 47°C — lethal to the hornet but survivable by the bees. European honeybees have no such defense.
Stinging Insects in Arizona?
Arizona has Africanized bees, paper wasps, and tarantula hawks. We identify and remove stinging insect nests safely.
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