The Vespidae are a large (nearly 5000 species), diverse, cosmopolitan family of wasps, including nearly all the known eusocial wasps (such as Polistes fuscatus, Vespa orientalis, and Vespula germanica) and many solitary wasps. Each social wasp colony includes a queen and a number of female workers with varying degrees of sterility relative to the queen. In temperate social species, colonies usually only last one year, dying at the onset of winter. New queens and males (drones) are produced towards the end of the summer, and after mating, the queens hibernate over winter in cracks or other sheltered locations. The nests of most species are constructed out of mud, but polistines and vespines use plant fibers, chewed to form a sort of paper (also true of some stenogastrines). Many species are pollen vectors contributing to the pollination of several plants, being potential or even effective pollinators, while others are notable predators of pest insect species. Although eight subfamilies are currently recognized, Raphiglossinae is likely also a valid subfamily. The subfamilies Polistinae and Vespinae are composed solely of eusocial species, while the Eumeninae, Euparagiinae, Gayellinae, Masarinae and Zethinae are all solitary with the exception of a few communal and several subsocial species. The Stenogastrinae are facultatively eusocial, considering nests may have one or several adult females; in cases where the nest is shared by multiple females (typically, a mother and her daughters) there is reproductive division of labor and cooperative brood care. In the Polistinae and Vespinae, rather than consuming prey directly, prey are masticated and fed to the larvae, which in return, produce a clear liquid (with high amino acid content) for the adults to consume; the exact amino acid composition varies considerably among species, but it is considered to contribute substantially to adult nutrition.