German yellowjacket

Description

German yellowjacket is a medium-sized, predatory, social, non-native wasp. It is native to Europe, Asia, and North Africa. It was unintentionally introduced into Canada in the 1960s and the eastern United States in the 1970s. It quickly spread and by 1989 it had reached California.

Adults are ½″ to ⅝″ long. The stout body is slightly wider than the head.

There are two large compound eyes, one on each side of the head; and three small simple eyes (ocelli) at the top of the head between the compound eyes. The yellow band behind the compound eye is continuous to the jaw (mandible), not narrowed or interrupted. The upper (dorsal) space between the compound eyes is entirely black—there is no yellow “eye loop”. The gap between the mandible and the compound eye is narrow, no more than the diameter of one ocellus. The distance between the rear ocellus and the hind margin of the upper surface of the head (vertex) is no more than the diameter of one ocellus. The face has three small black spots.

The antennae are long and black.

The dorsal surface of the largest section of the thorax (scutum) is black with no stripes down the middle. A yellow band at the leading edge of the pronotum is interrupted at the apex (nearest to the head).

The abdomen of the female has six segments, while that of the male has seven segments. The upper plate (tergum) of each abdominal segment is yellow with black markings. The first tergum has a diamond-shaped basal mark that is less than twice as wide as long. At least one of the remaining terga has a pair of black spots completely surrounded by yellow, not connected to the basal black mark.

The legs are yellow.

The wings are clear.

Size

Females: ½″ to ⅝″

Similar Species

Habitat

Ecology

Season

May to the first hard frost

Behavior

Worker wasps are short lived. Throughout their life they will perform 3 or 4 tasks, one at a time, at different stages of their life.

Life Cycle

In the spring a queen emerges from hibernation and mates with up to 7 males. In early summer she builds an embryonic nest. The papery nest is constructed from chewed wood fibers cemented with saliva. It is usually built underground but may also be built in an stump, attic, roof, hollow wall, or other sheltered part of a human structure. It begins as just three hexagonal cells, and into each cell she deposits a single egg. She continues building cells while caring for the grubs as they hatch. Through spring and summer the queen produces a large number of worker wasps. In late summer she begins producing queens and males. In Minnesota the nests do not survive the winter. Old queens, males, and workers are killed by cold weather in the fall, while new queens hibernate.

Larva Food/Hosts

Pre-chewed fragments of caterpillars and other soft-bodied insects.

Adult Food

Live arthropods; carrion; fruit; honeydew of aphids, caterpillars, and some scale insects; human processed food and garbage; and other sources of protein and sugar. Queens feed on flower nectar in the spring.