Length: Worker 12-18 mm.
Colour: Worker is black and yellow.
Yellow jackets prey on other insects but also scavenge. Since they forage over long distances, it is often difficult to locate their nests. There are four common species of yellow jackets in Ontario. The German yellow jacket is the most frequent pest species and makes the largest nests, with a possibility of more than 3000 wasps in a colony. The fertilized queen can usually be found over-wintering inside buildings or wood piles. In spring a new colony is established by the queen in a hollow stump, below ground in a cavity, in a wood pile even a hollow tree, or other protected voids such as an attic. The actual nest has many layers (combs) that are surrounded by paper, which is made from wood fires. Some species may also be suspended from eaves, roof rafters, and tree branches. Newly mated queens will over winter while males, un-mated females, and the old queens will die by late fall. The old nest will not be reused by these wasps.