downy yellowjacket

Uncommon

April through Autumn

This is a medium-sized, ½″ to ⅝″ long, predatory, social wasp. It closely resembles eastern yellowjacket. It is thought by some to be a hybrid between eastern yellowjacket (Vespula maculifrons) and common yellowjacket (V. alascensis). Others suggest that it probably arose as a hybrid but now queens mate with drones of the same species.

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 upper (dorsal) space between the compound eyes is entirely black—there is no yellow “eye loop”. The ridge on the rear of the head (occipital carina) is well developed through its entire length, and continues uninterrupted to the base of the jaw (mandible). The distance between the lateral ocelli and the occipital carina is about the same as the distance between the two lateral oceili. The yellow band on the area below the compound eye (gena) is continuous, not interrupted with black. The space between the bottom of the compound eye and the top of the mandible is narrow. The eyes touch, or almost touch, the mandibles.

The antennae are long and black. Males have 12 antennal segments, females have 13. The hardened plate at the base of each antenna is yellow, the rest is black. The under (ventral) side of the first antenna segment (pedicel) is black, not yellow.

The stout body is slightly wider than the head. The thorax is densely covered with long yellow hairs. A yellow band at the leading edge of the first section (pronotum) is interrupted nearest to the head (at the apex). The dorsal surface of the largest section (scutum) is black, and usually has no stripes down the middle.

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 varies in width but is usually V-shaped, without a narrow “neck” at the base. The second tergum usually does not have black spots surrounded by yellow (free).

The coloration of the thorax and abdomen is variable, some with more yellow (xanthic), others with more black (melanic). Xanthic individuals may have short yellow stripes on the scutum and small free black spots on the second abdominal tergum.

The legs are yellow.

The wings are clear.

Pre-chewed fragments of caterpillars and other soft-bodied insects, and probably nectar and honeydew.

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.

The overwintering queen emerges from hibernation in April or May. In early summer she builds an embryonic nest. The nest begins as just three hexagonal cells. Into each cell she deposits a single egg then covers the cell with fragile paper. She continues building 20 to 45 cells while caring for the grubs as they hatch. In about 30 days the workers emerge and take over nest building duties.

The nest is constructed underground from fecal matter and chewed wood fibers (carton) cemented with saliva. The carton is tan and fragile, but noticeably sturdier than that of eastern and common yellowjackets.

Through spring and summer the queen produces a large number of worker wasps. In mid-summer, the nest grows exponentially, as more and more workers become available, ultimately with 3,500 to 15,000 cells. In late summer the queen begins producing new 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. Only the new queens survive the winter. They mate with up to 7 males in the late summer or fall, then hibernate under loose tree bark, in a decaying stump, or in another sheltered location.

Sources: 24, 27, 29, 30.

What’s in a Name?
One of the common names for this newly identified (1978) species is hybrid yellowjacket. This refers to the possibility that it may be a hybrid between eastern and German yellowjackets.

Identification
In eastern North America, four yellowjacket species, common yellowjacket (Vespula alascensis), downy yellowjacket (V. flavopilosa), eastern yellowjacket (V. maculifrons), and German yellowjacket (V. germanica), closely resemble each other, making yellowjacket identification in this region difficult.

Pretty dry up here and the wasps are out in great numbers. So far, they aren't bothering the honey bees.

Location: Pennington Co. MN

Pretty dry up here and the wasps are out in great numbers. So far, they aren't bothering the honey bees.