Most of these are black and yellow; some are black and white like the bald-faced hornet. Others may have the abdomen background color of red rather than black. They can be identified by their distinctive markings, their occurrence only in colonies, and a characteristic, rapid, side to side flight pattern prior to landing. All females are capable of stinging. Despite having drawn the loathing of humans, yellow jackets are in fact important predators of pest insects.
Paper wasps are 0.7 to 1.0 inch long wasps that gather fibers from dead wood and plant stems, which they mix with saliva, and use to construct water-resistant nests made of gray or brown papery material. Paper wasps are also sometimes called umbrella wasps, due to the distinctive design of their nests. Nests can be found in sheltered areas, such as the eaves of a house, on tree branches, or on the end of an open pipe (for example, on an old clothesline pole). Unlike yellow jackets and hornets, which can be very aggressive, polistine paper wasps will generally only attack if they themselves or their nest are threatened. Since their territoriality can lead to attacks on people, and because their stings are quite painful and can produce a potentially fatal anaphylactic reaction in some individuals, nests in human-inhabited areas may present an unacceptable hazard.