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Species
Vespula pensylvanica Rohwer
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Vespula pensylvania, the western yellowjacket, is a social, ground-nesting wasp native to western North America. They aggressively protect their nests, and, like other vespid wasps, can sting repeatedly. Adult workers forage continually for high protein foods, mostly small insects, caterpillars, and spiders, and they sometimes scavenge on dead animals to feed their brood. Vespula pensylvania is found in all states west of the Rocky Mountains, from Mexico up through western Canada. Although it has a more limited distribution than either the closely-related and biologically similar common yellowjacket Vespula vulgaris or the German yellowjacket Vespula germanica (which have both recently become major pests in non-native habitats around the world, especially in the southern hemisphere) V. pensylvania also has a high potential for invasiveness.
Since 1919 there have been sporadic reports of the western yellowjacket in Hawaii, and in 1978, populations there exploded to become a public nuisance and threat to endemic Hawaiian insect fauna. A western yellowjacket queen starts to build a nest in the spring, which matures into a large colony of up to several thousand workers by fall. At this time the colony declines and only new queens overwinter. However, in warm climates, such as California and Hawaii, colonies can survive longer than the several summer months they last in their native range, growing to enormous size with the potential to devastate surrounding insect populations and create a large, difficult to control public nuisance. If their nests can be located, physically or chemically destroying them are effective means of population control. Toxic baits, in which attractants are laced with insecticides and offered to workers to feed to larvae and the queen can also be successful in destroying a colony. Baited traps are also used to monitor and assess population numbers.
Although Vespula pensylvania has similar yellow and black coloration patterns to other yellowjackets (wasps of the genera Vespula and Dolchivespula), the complete yellow ring around their eye is a reliable distinguishing characteristic.
(CABI 2011; Kweskin 2009; Wikipedia 2011)
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This species is black with yellow markings. The metasomal pattern is similar to V. germanica but Western Yellowjacket is the only species with a yellow ring around the compound ayes (Buck et al. 2008). In average the worker size is 15 mm (Gruner & Foote 2000). Head: Malar space less than half as long as the penultimate antennal segment; occipital carina complete; deeply emarginated subantennal mark on the frons. Metasoma: apex of 7th tergite depressed; tergum 7th densely pubescent apical margin; shaft of edeagus without sharp teeth at base of terminal spoon, aedeagus with slender preapical portion. Xanthic specimens are rare (Miller 1961, Buck et al. 2008).
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Rights holder/Author | Copyright © 2015 University of Alberta Museums |
Source | http://entomology.museums.ualberta.ca/searching_species_details.php?s=34538 |
Western Yellowjacket is native of western half of temperate North America in Canada, United States, Mexico and this species was introduced in Hawaii (Kweskin 2000, Carpenter & Kojima 1997). Canada: from Manitoba to British Columbia. United States: from western to Colorado, Nebraska, Texas and Wisconsin. México: Baja California Norte, Ciudad de Mexico and Michoacan (Buck et al. 2008).
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Rights holder/Author | Copyright © 2015 University of Alberta Museums |
Source | http://entomology.museums.ualberta.ca/searching_species_details.php?s=34538 |
Open boreal forest, forest edges and prairies. Urban zones as gardens, parkland, meadows and houses.
License | http://creativecommons.org/licenses/by-nc/3.0/ |
Rights holder/Author | Copyright © 2015 University of Alberta Museums |
Source | http://entomology.museums.ualberta.ca/searching_species_details.php?s=34538 |
They feed regularly on live prey. They are mostly predators of spiders, harvestmen, caterpillars, flies, hemipterans, soft beetles, butterflies, moths, crickets, slug and other bugs. This species avoids hard beetles. The adults carry their prey or part of them to the nest to feed their larval states. They also feed of flower nectar or sweet substances as aphid honeydew, they have been reported collecting dead honey bees and this species has affinity to scavenge in carrion (Akre et al. 1976, Kweskin 2000).
License | http://creativecommons.org/licenses/by-nc/3.0/ |
Rights holder/Author | Copyright © 2015 University of Alberta Museums |
Source | http://entomology.museums.ualberta.ca/searching_species_details.php?s=34538 |
In natural populations in cold zones the colony is annual, but in colonies inside buildings the wasp survive the winter.
License | http://creativecommons.org/licenses/by-nc/3.0/ |
Rights holder/Author | Copyright © 2015 University of Alberta Museums |
Source | http://entomology.museums.ualberta.ca/searching_species_details.php?s=34538 |
The Western Yellowjacket is a social species with annual colonies. In early April or late May the queens emerge from diapauses and them looking for nesting places, generally they fly 20 cm above the ground; most queens begin the nest in deserted rodent burrows, but they are also built in other dark cavities like hollow walls and attics (Akre et al. 1976, Akre et al. 1981, Buck et al. 2008). The successful queen burrows about 10-30 cm underground, aerial nest are uncommon. The queen adds cells inside the nest, she lays eggs and takes care of the larvae, the first workers emerge in early June and the queen doesn’t leave the nest again. The workers search food and fibers, care the larvae, clean the cells, feed the queen, the larvae and the males, they exhibit trophallaxis, mauling and ovoposition behavior, and also they protect the colony (Akre et al. 1976). The average of lifespan of a worker is 34 days. The males emerge in mid August, finally the colony decline in later September (Akre et al. 1976).
License | http://creativecommons.org/licenses/by-nc/3.0/ |
Rights holder/Author | Copyright © 2015 University of Alberta Museums |
Source | http://entomology.museums.ualberta.ca/searching_species_details.php?s=34538 |
Barcode of Life Data Systems (BOLDS) Stats
Public Records: 0
Specimens with Barcodes: 6
Species With Barcodes: 1
This species is very common and this is not reported in vulnerability status.
License | http://creativecommons.org/licenses/by-nc/3.0/ |
Rights holder/Author | Copyright © 2015 University of Alberta Museums |
Source | http://entomology.museums.ualberta.ca/searching_species_details.php?s=34538 |