Western Yellowjacket
( Vespula pensylvanica )


2012-1001-43110003-HYM00394-Vespula_pensylvanica[1330h00s,L,A,dorsum]{EStrand}1-G.jpg

PHOTO COMMENT

IDENTIFICATION
Identification:Vespula pensylvanica
(de Sausser, 1857)
Common Name:Western Yellowjacket
Life Stage:(A) adult

PHYLOGENY

Phylum:Arthropoda
Class:Insecta
Superorder:Holometabola
Order:Hymenoptera
Suborder:Apocrita
Family:Vespidae
Genus:Vespula
Taxon Code:HYM00394
ITIS TSN#:154277

LOCATION DETAILS
Location
Palo Alto Animal Services, Palo Alto, Palo Alto
County:Santa Clara County
ECI Site#:CA43110000

RECOGNITION
This wasp is distinguished from other yellowjackets by the unbroken yellow ring encircling its compound eyes. Secondarily, on the frons, below the antennae, there is a spotted area. Third, the first antennal segment bears a yellow blotch. V. pensylvanica is similar to V. germanica. However, its upper eye margins are not completely encircled in yellow.
Colors
Black and yellow patterning similar to most other yellowjackets.

BIOLOGY
Food
Yellowjackets forage for insects and dead animals for meat and plant nectar for carbohydrates. The captured prey is typically taken to a more vertical surface and malaxated by chewing off legs and wings.
Nesting
Western Yellowjackets build large nests made of wood fibers, enclosed in a hexagonal paper envelope with a small 10– to 30-cm entrance tunnel at the bottom. Nests are usually found 10–15 cm below ground or in other dark cavities, such as rodent burrows.
Development
Fertilized queens emerge in the Spring to found new colonies. In rare cases a colony may remain active through a mild winter. Usually, a queen colonizes a rodent burrow or other cavity and builds a small nest. She continues to forage for building materials and food until 4-7 workers emerge and take over these duties. The queen then devotes herself to laying eggs. By Fall reproductive progeny have left to mate and start new colonies. The colony declines in numbers. Males perish. Newly fertilized queens overwinter until Spring. Worker lifespan ranges from 22-40 days.
Importance
V. pensylvanica is predatory and feeds on a wide range of invertebrates, including pests in gardens. In also is a scavenger on carrion. As a stinging insect it is a pest to humans, pets, livestock and other domesticated animals.
Range
The western half of the United States, including South Dakota and Hawaii, and north into British Columbia and Alberta.

HABITAT
V. pensylvanica can be found in open forest, prairies, urban zones, gardens, parkland, meadows, and houses.

CREDITS
Photographer
Erica Strand

REFERENCES
  • Species Vespula pensylvanica - Western Yellowjacket. (http://bugguide.net/node/view/12981). Accessed March 12, 2016. [ IMAGES ]
  • Integrated Taxonomic Information System TSN#154277
  • Vespula pensylvanica. (https://en.wikipedia.org/wiki/Vespula_pensylvanica). Accessed April 8, 2017.


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