Wasps of the cosmopolitan genus Polistes (the only genus in the tribe Polistini) are the most familiar of the polistine wasps, and are the most common type of paper wasp in North America. Walter Ebeling coined the vernacular name "umbrella wasps" for this genus in 1975 to distinguish it from other types of paper wasp, in reference to the form of their nests. It is also the single largest genus within the family Vespidae, with over 300 recognized species and subspecies. Their innate preferences for nest-building sites leads them to commonly build nests on human habitation, where they can be very unwelcome; although generally not aggressive, they can be provoked into defending their nests. All species are predatory, and they may consume large numbers of caterpillars, in which respect they are generally considered beneficial. The European paper wasp, Polistes dominula, was introduced into the US about 1981 and has quickly spread throughout most of the country, in most cases replacing native species within a few years. This species is very commonly mistaken for a yellow jacket, as it is black, strongly marked with yellow, and quite different from the native North American species of Polistes. The cuckoo wasp, Polistes semenowi, is an obligate social parasite, whose only host is P. dominula. Polistes metricus adults malaxate (malaxate means knead or rub [stuff] to make it soft) their insect prey by chewing them into a pulp, sucking out and ingesting the body fluids, then feeding the rest of the morsel to their larvae. The most widely distributed South American wasp species, Polistes versicolor, is particularly common in the southeastern Brazilian states. This social wasp is commonly referred to as the yellow paper wasp due to the distinct yellow bands found on its thorax and abdomen. Polistes wasps can be identified by their characteristic flight; their long legs dangle below their bodies, which are also more slender than a yellow jacket.