Yellowjacket Wasp
( Vespula sp. )


2011-0820-EB410001-HYM00440-Vespula_sp[1539h41s,F,A,remains]{EXD}-G.jpg

PHOTO COMMENT

IDENTIFICATION
Identification:Vespula sp.
(Thomson ,1869 )
Common Name:Yellowjacket Wasp
Life Stage:(A) adult

PHYLOGENY

Phylum:Arthropoda
Class:Insecta
Superorder:Holometabola
Order:Hymenoptera
Suborder:Apocrita
Family:Vespidae
Genus:Vespula
Taxon Code:HYM00440
ITIS/TSN:154274

LOCATION DETAILS
Location Name
Pleasanton Ridge Regional Park, Pleasanton Ridge Regional Park, Pleasanton Ridge Regional Park, Foothill Road, Pleasanton, CA, Sunol
County:Alameda County
ECI Site#:CAEB410000
Open Space Location:Pleasanton Ridge Regional Park

RECOGNITION
Description
Yellowjackets have a general resemblance to bees. They are the same size as bees and do not have the characteristic narrow wasp-like waist. Yellowjackets have jagged bands of bright yellow and black on the abdomen. In comparison, honeybees are light brown and black.
Body Length
Q: 16-19 mm. W: 11-15 mm.
Diversity
Thirteen species of Vespula in North America (twelve native, and one exotic, V. germanica).
Child Taxa
German Yellowjacket (V. germanica); Western Yellowjacket (V. pensylvanica); Forest Yellowjacket (V. sulphurea)
Colors
Color1: yellow Color2: black

BIOLOGY
Food
Predaceous; or scavengers.
Nesting Preferences
Yellowjackets commonly build nests in rodent burrows, but they sometimes select other protected cavities, such as voids in walls and ceilings of houses, as nesting sites. Colonies, which are begun each spring by a single reproductive female, can reach populations of between 1,500 and 15,000 individuals, depending on the species. The wasps build a nest of paper made from fibers scraped from wood mixed with saliva. It is built as multiple tiers of vertical cells, similar to nests of paper wasps, but enclosed by a paper envelope around the outside that usually contains a single entrance hole. If the rodent hole isn't spacious enough, yellowjackets will increase the size by moistening the soil and digging.
Importance
In the Bay Area and the Western United States there are two distinct types of social wasps - yellowjackets and paper wasps. Yellowjackets, especially the ground- and cavity-nesting varieties defend their nests vigorously when disturbed. They become more aggressive as the season progresses and colony populations become larger while food becomes scarcer. They also are beneficial by killing large numbers of plant-feeding insects and nuisance flies. Wasps become a problem only when they threaten to sting humans. In California, Yellowjackets are the primary pests among the social wasps.
Diversity
Thirteen species of Vespula in North America (twelve native, and one exotic, V. germanica).
Importance
In the Bay Area and the Western United States there are two distinct types of social wasps - yellowjackets and paper wasps. Yellowjackets, especially the ground- and cavity-nesting varieties defend their nests vigorously when disturbed. They become more aggressive as the season progresses and colony populations become larger while food becomes scarcer. They also are beneficial by killing large numbers of plant-feeding insects and nuisance flies. Wasps become a problem only when they threaten to sting humans. In California, Yellowjackets are the primary pests among the social wasps.
Development
Typically, previously mated, overwintering yellowjacket and paper wasp queens begin their nests in spring when the weather becomes warm. The queen emerges in late winter to early spring to feed and start a new nest. From spring to midsummer, nests are in the growth phase, and larvae require large amounts of protein. Workers forage mainly for protein at this time (usually other insects) and for some sugars. By late summer, however, the colonies grow more slowly or cease growth and require large amounts of sugar to maintain the queen and workers; foraging wasps are particularly interested in sweet things at this time. Normally, yellowjacket and paper wasp colonies live only one season. In very mild winters or in coastal California south of San Francisco, however, some yellowjacket colonies survive for several years and become quite large.

CREDITS
Photographer
Eddie Dunbar
Insect Sciences Museum of California

References
Genus Vespula. (http://bugguide.net/node/view/554). Accessed March 12, 2016. .
ITIS.
Yellowjackets and Other Social Wasps. UC Pest Notes. (http://www.ipm.ucdavis.edu/PMG/PESTNOTES/pn7450.html)


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