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W*H*Y Wednesday: The Western Yellowjacket

Today's post closes out the W*H*Y Wednesday series we started in Fall 2008 that focused on each of the 20 species caught in the W*H*Y Trap for Wasps, Hornets & Yellowjackets.

Last, but certainly not least, is Vespula pensylvanica, the Western Yellowjacket.

Pensylvanica_Western_YJ_Queen Western Yellowjackets are most easily identified by the yellow ring surrounding the upper portion of the eye, commonly called an “eye loop”.  Their abdominal markings closely resemble that of the German Yellowjacket, marked with a black diamond on the uppermost segment.  Roughly a half inch in length, like other yellowjacket species, they will have stout bodies, black antennae and yellow legs.

The Western Yellowjacket is found not only in the Western U.S., but also the Upper Midwest, as illustrated in the map below:


Western Yellowjackets will scavenge for protein and sugar, becoming "picnic pests". This species is known to create severe problems for loggers, fruit growers and those engaged in outdoor activities.

Pensylvanica_Western_YJ_nest The majority of Western Yellowjacket nests are found in abandoned rodent burrows, but they've also been found in attics and building walls. Colonies range from 1000 to 5000 workers at peak size. In warmer climates, entire colonies can overwinter -- not just the queen.

Western Yellowjackets may be a hazard if agitated while scavenging. They are also a stinging hazard if the nest is disturbed. Western Yellowjackets can be very annoying to humans, since they are likely to be found near human activity.

Here's a video we shot of a Western Yellowjacket nest, located under the front steps of a house:

WHYTR_200dpi Good news if you have this species in your back yard: the W*H*Y Trap from RESCUE! will catch Western Yellowjackets!

February 11, 2009 in Entomology, Science, WHY Trap, Yellowjackets | Permalink


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