Megachilidae is a cosmopolitan family of mostly solitary bees whose pollen-carrying structure is restricted to the ventral surface of the abdomen. Megachilid genera are most commonly known as mason bees and leafcutter bees, reflecting the materials from which they build their nest cells ; a few collect plant or animal hairs and fibers, and are called carder bees, while others use plant resins in nest construction and are correspondingly called resin bees. All species feed on nectar and pollen, but a few are kleptoparasites, feeding on pollen collected by other megachilid bees. Parasitic species do not possess scopae. The motion of Megachilidae in the reproductive structures of flowers is energetic and swimming-like; this agitation releases large amounts of pollen.
Halictidae is the second-largest family of bees with nearly 4,500 species. Halictid species are an extremely diverse group that can vary greatly in appearance. These bees occur all over the world and are found on every continent. Usually dark-colored and often metallic, halictids are found in various sizes, colors and patterns. Several species are all or partly green and a few are red, purple, or blue. A number of them have yellow markings, especially the males, which commonly have yellow faces, a pattern widespread among the various families of bees. The family is one of many with short tongues and is best distinguished by the arcuate basal vein found on the wing. Females in this family tend to be larger than the males.
With over 850 species, the genus Nomada is one of the largest genera in the family Apidae, and the largest genus of kleptoparasitic "cuckoo bees." Kleptoparasitic bees are so named because they enter the nests of a host and lay eggs there, stealing resources that the host has already collected. The name "Nomada" is derived from the Greek word nomas, meaning "roaming" or "wandering."
Charles Robertson (1858–1935) was an American entomologist specializing in bees. He carried out what is still the single most intensive study of flower-visiting insects of a single locality, culminating in a 221-page book published in 1928 under the title Flowers and Insects.
Coelioxys, common name leaf-cutting cuckoo bees or sharp-tailed bees , is a genus of solitary kleptoparasitic or brood parasitic bees, belonging to the family Megachilidae.
Nomada marshamella, Marsham's nomad bee, is a species of Palearctic cuckoo bee which appears to be a wasp mimic and which is cleptoparasite on the mining bees of the genus Andrena, especially A. scotica and A. trimmerana.
Sphecodes gibbus, the dark-winged blood bee, is a species of cleptoparasitic blood bee from the Palearctic. It is the type species of the genus Sphecodes and was first described by Carl Linnaeus as Sphex gibba in 1758.
Andrena vaga, the grey-backed mining bee, is a species of solitary bee which is found in most of Europe but which is very rare in Great Britain, where it may be recolonizing in the south-east after previously being extirpated. It specialises in feeding on the pollen of willows.
