A suite of megachilid rely on plant resins for nest construction. These "resin bees" are typically smaller than honey bees, and effective pollinators, although the hard glue-like resins can complicate management of other tunnel nesting bees. Carder bees, "Anthidium", are unique for using plant fibers; there are 80 to 90 species of them in North America. Ironically, a non-native is best known—"A. manicatum", the European wool carder bee, was accidentally introduced to the Americas in the late '60s and has now spread across the continent. It has been described as "... perhaps the most widely distributed unmanaged bee species in the world." Like most "Anthidium", rather than cutting leaves or petals, "A. manicatum" scrapes the hairs from leaves to use for nesting material. It is atypical because the male is larger than the female and constantly on patrol, protecting a "harem" by chasing and even attacking all interlopers including honey and bumble bees, its tail equipped with multiple prongs that can knife in between the segments of almost any intruder.