pecies are pollen feeders and may be important pollinators. Several genera and species of halictids are cleptoparasites of other bees (mostly other halictids). The most well-known and common are species in the genus Sphecodes, where the female enters the cell with the provision mass, eats the host egg, and lays an egg of her own in its place.
Halictidae are one of the four bee families that contain some species that are crepuscular. These bees are active only at dusk or in the early evening or sometimes truly nocturnal. In these cases they have greatly enlarged ocelli or simple eyes to enhance their night vision.
Megachilidae-Leaf Cutting Bees and Mason Bees. The Megachilidae are a cosmopolitan family of solitary bees (Figure 50) whose pollen-carrying structure (called a scopa) is restricted to the ventral surface of the abdomen (rather than mostly or exclusively on the hind legs as in other bee families).
Leaf Cutting Bee with Pollen Trapped on Underside of Abdomen.
Megachilid genera are most commonly known as mason bees and leafcutter bees, reflecting the materials they build their nest cells from (soil or leaves, respectively); a few collect plant or animal hairs and fibers, and are called carder bees. All species feed on nectar and pollen, but a few are cleptoparasites (informally called "cuckoo bees"), feeding on pollen collected by other megachilid bees. These parasitic species do not possess scopa and are incapable of collecting their own pollen. The brightly colored scopa leads to a colloquial name used occasionally in North America - "Jelly-belly bees." Megachilid bees are among the world's most efficient pollinators because of their energetic swimming-like motion in the reproductive structures of flowers, which moves pollen, as needed for pollination. One of the reasons they are efficient pollinators is their frequency of visiting to plants. In actuality they are extremely inefficient at gathering pollen when compared to all other bee families. However, megachilids require on average nearly ten times as