While walking along the Little Truckee River (CA) I noticed a large common aerial yellowjacket (Dolichovespula arenaria) nest built near the ground in some shrubs.
Yellowjackets are the common name given to wasps in the Vespa and Dolichovespula genera. These predatory insects have a black and yellow body, black antennae and brown wings. The body patterns are quite variable. Yellowjackets can sting repeatedly with the barbed, lance-like stinger located at the end of the abdomen. The main purpose of the stinger is for defense. The venom paralyzes prey. Some humans have an allergic reaction to the venom. Usually though, unless a person is stung repeatedly, the venom does no major harm to people.
The common aerial yellowjacket nest is football shaped and is built hanging from a tree or building or can be located in bushes near the ground, as this nest is. The yellowjackets chew wood and mix the wood fibers with saliva to make a papery construction pulp. The nest is formed of multiple stacked combs (made of the papery wood fibers) completely surrounded by a papery envelope. A single entrance hole is located near the bottom of the nest. Each fall the nest is abandoned and not reused.
Yellowjackets are social insects that create an annual colony. In the fall an inseminated female queen seeks a protected shelter under bark or inside human dwellings. All of the other yellowjackets in the colony die. In early spring the queen emerges and builds a small paper nest where she lays eggs. The larva that hatch are feed by the queen until they pupate and emerge as infertile workers. These new workers then begin to brood the queen. From this point on the colony, and nest, expand rapidly as the workers forage for food, defend the nest and care for the queen and more larva. In August or September the nest reaches its maximum size. New males and queens are produced at this time of maximum nest expansion. The males and queens emerge from the nest and mate after which the inseminated queens seek shelter for the winter and the males die. The yellowjackets remaining in the colony die as winter approaches.
Adult yellowjackets feed on nectar and the juice of fruit but are omnivores and destroy many insects that damage shade and crop trees, houseflies and blowflies. Even though yellowjackets can become a nuisance at picnics and campgrounds, they are truly a beneficial insect and should not be killed unless a danger to humans. The benefits of yellowjackets are difficult to appreciate when they attempt to share a picnic lunch.
I did not have anything with me to scale the nest so just placed my straw hat above the nest for a picture to illustrate the size – at least as large as a basketball.