Melittidae
Macropis
Loosestrife Oil Bees

In Minnesota, the family Melittidae includes one genus — Macropis. Bees in this genus are pollen- and oil-collecting specialists of plants in the genus Lysimachia (loosestrife). Three Macropis species occur in Minnesota and all three species are rare. Macropis nuda has the broadest range and most county occurrences of the three species. Bees in the genus Macropis nest belowground and typically exacavate very shallow nests (a few inches deep) in well-drained soil. Macropis use the collected Lysimachia floral oils in two ways: first, to waterproof their nest and second, to add to the pollen provisions provided for the larvae (in lieu of nectar). 

Macropis are small- to medium-sized black bees with interrupted thin white hair bands on the rims of the third and fourth tergites (abdominal segments). Bees in this genus have two forewing submarginal cells and a short glossa (tongue). Males have a yellow clypeus; females have pollen-collecting hairs on their hind leg tibiae and sponge-like oil-collecting hairs on their foreleg and mid-leg basitarsus. Macropis range in length from 5 to 12 mm (0.2 to 0.47 inches).