Yellowjackets, commonly referred to as meat bees, are social wasps that live in colonies. They are often confused with bees. They are a more aggressive threat than bees. They do not have barbs on their stingers so they can sting more than once. They can also bite. Vespula pensylvanica is primarily a scavenger and in the summer months adults are common around garbage recepticles in picnic and barbeque areas. Nests are usually constructed in abandoned rodent burrows or in house walls and attics. Nests contain 500 to 5,000 workers and start to decline in late September to October. The colony usually reaches its peak in late summer. At the end of the summer new males and queens are produced and mate for overwintering. The males and worker yellow-jackets die off and the fertilized queen seeks a place to hibernate through winter.