• Family: Megachilidae
• Approximate # species in region: 29
• Common name: leaf-cutter bees, resin bees

Megachile is a widespread and highly diverse genus of bees. They range in size from about one-quarter the size of a honey bee, to nearly twice as large. Megachile females transport pollen beneath their abdomens (often holding up their abdomens while foraging). They are united by their varied nesting strategies. Females build linear nests that they line with natural materials such as leaves, plant fibers, resin, petals, and in some cases artificial materials like plastic bag pieces. Although they are most well known as inhabitants of bee hotels, many species can nest both above and below ground, and still others prefer to nest exclusively below ground.

Megachile are similar in appearance to several other megachilid genera. The phenology of Osmia averages earlier in the year than Megachile (in our region, Megachile aren’t likely to be found before May), but still overlaps extensively. Unlike most Osmia, Megachile have nonmetallic, black integument and often have bold hair bands on the abdomen. Some nonmetallic Osmia (e.g., O. bucephala) have black-and-white bumble bee-like patterns similar to some Megachile (subgenus Xanthosarus), but note that the Osmia appear more blockheaded and rotund – similar Megachile have less rounded abdomens that are more pointed at the tip and almost spade-shaped when viewed from above. Small, elongate Megachile species (subgenus Chelostomoides) might be confused for Hoplitis, but these Megachile have darker black or grayish eyes, unlike the lighter greenish eyes of Hoplitis.

Regional Species List: