Western Yellowjacket
Vespula pensylvanica
In mild climates like Hawaii where colonies do not freeze out in winter, they can form massive multi-queen supercolonies containing millions of workers.
- Scientific name
- Vespula pensylvanica
- Taxonomy
- Animalia › Arthropoda › Insecta › Hymenoptera › Vespidae › Vespula
- IUCN Red List status
- Least Concern
- Population trend
- stable
- Biome
- forest
- Habitat
- Temperate forests, woodland edges, meadows, agricultural lands, and urban gardens.
- Diet
- Omnivorous; adults consume floral nectar, tree sap, and fruit juices, while hunting insects and scavenging meat to feed larvae.
- Range
- Western North America, Pacific Northwest, Rocky Mountains, Hawaii (introduced)
- Size
- Workers are 10–12 mm long; queens reach 15–19 mm.
- Lifespan
- Workers live 2 to 3 weeks; queens survive up to 1 year.
- Active
- diurnal
- Threats
- Pesticide application, severe winter frosts, and habitat clearing.
- Safe to approach?
- Defensive and potentially dangerous. Western yellowjackets can sting repeatedly without losing their stinger. Maintain a calm distance, especially from ground burrows or picnic areas, and avoid swatting at them. If stung, wash the site with soap and water, apply a cold pack, and seek immediate emergency medical care if signs of a severe allergic reaction (anaphylaxis) develop.
The western yellowjacket ( Vespula pensylvanica ) is a Nearctic species of wasp in the genus Vespula . It is native to regions of North America, largely in areas with northern temperate climates. Its reproductive behavior is constrained by cold weather, which successfully reduces the number of western yellowjackets in cold months. However, in the absence of cold weather, this wasp's population can explode. The western yellowjacket has become particularly invasive in the Hawaiian Islands, resulting in their label...
Photo: Eugene Zelenko, CC-BY-SA, via iNaturalist
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