Megachile rotundata

Megachile rotundata, the alfalfa leafcutting bee, is a European bee that has been introduced to various regions around the world. As a solitary bee species, it does not build colonies or store honey, but is a very efficient pollinator of alfalfa, carrots, other vegetables and some fruits. Because of this, farmers often use M. rotundata as a pollination aid by distributing M. rotundata prepupae around their crops. Each female will construct and provision her own nest, which is built in old trees or log tunnels. Being a leafcutter bee, these nests are lined with cut leaves. These bees feed on pollen and nectar and display sexual dimorphism. This species has been known to bite and sting, however it poses no overall danger unless it is threatened or harmed and its sting has been described as half as painful as a honey bee's. Megachile rotundata is a member of the subfamily Megachilinae, which includes more than 4000 bee species; this currently makes this family the second largest among all other bee families. This subfamily is one of four other subfamilies of Megachilidae, the other three being Fideliinae, Pararhophitinae, and Lithurginae. Phylogenetic studies suggest that this subfamily is monophyletic. More specifically, it belongs to the genus Megachile, which contains 52 subgenera and 1,478 species. This genus Megachile consists of bees which cut leaf pieces to line their nests. Megachile rotundata is a European leaf-cutting bee placed in the sub-genus Eutricharia, the 'small leaf-cutting bees'; they are 6–9 mm (0.24–0.35 in) in length. They are partially bivoltine, meaning that under the right conditions they can produce two generations per year. These bees present a sexual dimorphism, in which the males are smaller than the females and differently marked. M. rotundata bees are a dark grey color. Females have white hairs all over their bodies, including on their scopae. In contrast, males have white and yellow spots on their abdomens. Megachile rotundata is currently found on all continents except for Antarctica. In North America, the species was deliberately imported to assist in the pollination of food crops, but has now become feral and widespread. In New Zealand and Australia, M. rotundata was also introduced to assist in the pollination of alfalfa (known locally as lucerne), in 1971 in New Zealand, and 1987 in Australia.