Originally Posted by DBS.US

All wasps will defend their nests, but the Yellow Jackets and hornets are the most aggressive. They can be distinguished from bees by their thin "waists." Bees are thick-waisted. They fold their wings lengthwise when at rest. Like all wasps, yellow jackets prey on a variety of insects and other arthropods. Yellow jackets will also forage on foods that people eat, especially sweets and meats.

They are considered beneficial insects, eating other insects. The yellow jacket colony will remain active for only one summer, after which the queens will fly away to start more colonies. The remaining ones, die at the end of the summer, the nest is not reused.
(more)