Paper wasps can and will sting in defense of their nest, or when threatened. Unlike honey bees, which have barbed stings and can only sting once, paper wasps can sting multiple times. A paper wasp can call other colony members using alarm pheromones, chemical messages that tell other wasps to help defend the nest from a threat. Try to stay calm and avoid swatting at paper wasps.
Yellowjacket is the common name in North America for predatory wasps of the genera Vespula and Dolichovespula. Members of these genera are known simply as "wasps" in other English-speaking countries. Most of these are black and yellow; some are black and white (such as the bald-faced hornet, Dolichovespula maculata) while others may have the abdomen background color red instead of black. They can be identified by their distinctive markings, small size (similar to a honey bee), their occurrence only in colonies, and a characteristic, rapid, side to side flight pattern prior to landing. All females are capable of stinging. Yellowjackets are important predators of pest insects.