Asian Hornet (Yellow-Legged Hornet)

Vespa velutina — the Asian hornet (also called the yellow-legged hornet) — is one of the most economically damaging INVASIVE INSECT PESTS to emerge in Europe in the past 20 years and one of about 22 species in genus Vespa (the true hornets — same genus as the European hornet Vespa crabro and the Asian giant hornet Vespa mandarinia, both already in the Wild Files). The species is native to southeastern Asia (especially China, Vietnam, Indonesia) but was accidentally introduced to France in 2004 — first detected in southwestern France in 2004, almost certainly introduced via a shipment of pottery from China that included a hibernating queen. The species has spread rapidly across Europe over the past 20 years and is now established across most of France, Spain, Portugal, Italy, the UK (since 2016), Belgium, Netherlands, Germany, Switzerland, and is continuing to spread. Adults are 2-3 cm long (smaller than the Asian giant hornet but still substantially larger than European honey bees), with the species' diagnostic features: dark BROWN-AND-BLACK BODY with a single yellow-orange band on the abdomen (much darker overall than European hornets), and BRIGHT YELLOW LEGS (the source of the alternative 'yellow-legged hornet' common name — the bright yellow leg color distinguishes Asian hornets from native European hornets which have darker legs). Workers and queens have powerful stings (similar to European hornets, capable of delivering medically-significant pain and (in highly-allergic individuals) anaphylactic reactions). The species is a MAJOR THREAT to European HONEY BEE populations. Asian hornets are EXCEPTIONAL HONEY BEE PREDATORS — workers hover in front of beehives and INTERCEPT RETURNING HONEY BEE FORAGERS, capturing the bees mid-air or as they approach the hive entrance. Captured bees are taken back to the hornet nest and fed to developing wasp larvae. Honey bees in the species' Asian native range (Apis cerana) have evolved a 'BEE BALL' DEFENSE in which dozens of bees surround a hornet attacker and overheat it to death by simultaneously flexing their flight muscles to elevate body temperature above the hornet's lethal limit. EUROPEAN HONEY BEES (Apis mellifera) DID NOT EVOLVE WITH ASIAN HORNETS and lack effective defenses against the introduced predator — affected European apiaries can lose entire colonies to sustained Asian hornet predation. A single Asian hornet colony can kill THOUSANDS OF HONEY BEES PER DAY, with affected apiaries showing dramatic colony decline and increased honey bee colony losses. The species is the focus of major European agricultural and beekeeping pest management programs — extensive trapping campaigns, nest destruction (the species builds large secondary nests up to 1+ m diameter in tree canopies), and public-education campaigns aim to slow the species' spread. The species is the foundational case study in modern textbook discussions of NEWLY-EMERGING INVASIVE HORNET pests in Europe.