German Yellowjacket

Vespula germanica — the German yellowjacket — is the most cosmopolitan invasive yellowjacket on Earth and one of the most ecologically disruptive invasive Hymenoptera in the modern world. Native to Eurasia (Europe, North Africa, parts of central Asia), the species has been accidentally introduced via shipping cargo to North America (Ohio 1975, now established across most of US and southern Canada), South America (Argentina, Chile, Brazil), Australia (Tasmania 1959, mainland 1977), and New Zealand (1940s). Adults are 12-15 mm long with the family-typical bright yellow-and-black banded pattern. Colonies are founded in spring by single overwintered queens, who excavate underground or wall-void nests; colonies grow through summer to peak populations of 3,000-10,000 workers (much larger than most native temperate yellowjacket species). In invaded ranges, German yellowjackets cause substantial ecological damage. New Zealand has the highest documented density of yellowjacket biomass per hectare anywhere in the world — South Island beech forest contains an estimated 10,000 active German yellowjacket colonies per hectare, with total wasp biomass approximately 10x the biomass of native bees, native parasitoid wasps, and native ant communities combined. The wasps deplete the honeydew secreted by Ultracoelostoma scale insects (a critical food source for native New Zealand kaka, kakariki, and tui birds), and they actively hunt and kill native invertebrate fauna. Australia and Tasmania experience similar but slightly less extreme impacts. North American invasion has been less ecologically catastrophic but has displaced several native Vespula species and become a major late-summer nuisance pest at outdoor activities. The species' aggressive late-summer foraging behavior (workers seek protein and sugar to support reproductive brood production) brings the species into conflict with picnics, outdoor dining, and trash receptacles — and the resulting human-wasp interactions cause thousands of stings per year worldwide. The species' sting is rated 2.0 on the Schmidt Sting Pain Index — comparable to honey bee. The Wild Pest service area sees V. germanica annually in Metro Vancouver as a continuing residential and commercial pest.