Vespula

Taxonomy

Order: Hymenoptera
Family: Vespidae
Subfamily: Vespinae
Genus: Vespula Thomson, 1869
Common names: yellowjackets, yellow jackets, meat bees

Common name

yellowjackets

Background

The genus Vespula is a small group of 14 species. They are widely distributed in North America and Eurasia. A few species are invasive across the globe. Several species, including V. alascensis and V. pensylvanica, are scavengers of protein and carbohydrate-rich foods, feeding on road kill and garbage and as a result frequently come in contact with humans. Vespula nests are largest in the late summer. They can be aggressive and will sting repeatedly when threatened.

How to separate from NGH

• Most yellowjackets are significantly smaller than northern giant hornets; workers average around half an inch in length for many species
• Many species are brightly marked with yellow and black bands

Distribution

Yellowjackets are found around the world, with fourteen species in North America, of which one is exotic (V. germanica). Vespula germanica was established in the United States by the late 1960s, as well as southern South America, Australia, South Africa, and New Zealand. The largest number of Vespula species occur in the northern United States and southern Canada (Carpenter and Kojima 1997).

Distribution map of Vespula by GBIF: https://www.gbif.org/species/1311631

Diagnostic characteristics

Vespula is most commonly confused with its sister genus Dolichovespula, but can be distinguished by the following:

• The shorter oculomalar space and rounder face in Vespula
• Vespula are more likely to nest underground than Dolichovespula

Vespa species can be distinguished from Vespula species by:

• The postocular distance is more than twice as broad as the distance between the hindocelli
• The head in dorsal view greatly expanded behind eyes, and is not expanded in Vespula and Dolichovespula

Diversity

(from Carpenter and Glare 2010):

common yellowjacket (V. alascensis), originally known as V. vulgaris
prairie yellowjacket (V. atropilosa)
forest yellowjacket (V. acadica)
blackjacket (V. consobrina)
cuckoo yellowjacket (V. infernalis)
northern red-banded yellowjacket (V. intermedia)
eastern yellowjacket (V. maculifrons)
hybrid yellowjacket (V. flavopilosa)
western yellowjacket (V. pensylvanica)
German yellowjacket (V. germanica)
southern yellowjacket (V. squamosa)
California yellowjacket (V. sulphurea)
widow yellowjacket (V. vidua)

Host/prey associations

Yellowjackets may have a very diverse diet. Most species prey on insects to feed their young, and consume insects, nectar, and other sugar sources as adults. Several species are opportunist scavengers and will feed on a diversity of protein sources, such as carrion and processed meats, as well as carbohydrate sources including soft drinks, sweets, and even beer. Vespula species will also scavenge dead honey bees (Apis mellifera) found outside beehive entrances in the late summer (Coelho and Hoagland 1995).

Nesting and general behavior

Yellowjackets build their nests underground or in protected above ground cavities. The nests are built of paper made from a mixture of plant fibers and saliva. Unlike paper wasps, the brood cells are enclosed in a paper envelope. New queens generally start their nests in preexisting cavities, such as vacant rodent burrows or hollow logs or trees. A few species will nest in manmade structures like attics, abandoned cars, and wall voids. Nest size varies depending on the species involved and the region. Some nests may be hand-sized, with a relatively small number of workers, whereas nests in warmer climates may much larger, with thousands of workers. Perennial colonies sometimes occur in warm climates, and they can become enormous. This may occur when the new queens that emerge in the fall mate and then rejoin an active colony.

Known invasives

The German yellowjacket (Vespula germanica) was introduced to the United States and established by the late 1960s. This species has spread to other regions as well, including southern South America, Australia, South Africa, and New Zealand.