Megachile pugnata

Taxonomy

Megachile pugnata is in the Sayapis subgenus within the Megachile genus. The genus Megachile is known by the common name “leafcutter bees” because many members cut out circular or oval pieces of leaves and use them to line their nests. There are some exeptions; some Megachile use tree resin and others use chewed vegetation and mud in addition to leaf pieces. M. pugnata were fairly common in Bee Atlas blocks throughout the state, but were most common in the southern part of the state and least common in the northeast.

Description

Megachile are primarily characterized by having large chewing mandibles and scopae (pollen-collecting hairs) on the underside of the abdomens of females. Megachile pugnata, like many Megachile species, is a mostly dark bee with light hair bands across the females' abdomens. They are a large Megachile, almost as big as Osmia lignaria. The males have elaborately modified forelegs with yellow coloring and hair extending from the lower portions. Females are less tolerant of conspecifics than many solitary bees and have a habit of displaying their mandibles open when disturbed. They are a fun bee to observe at blocks.

Nest Structure

Megachile pugnata use cut leaf pieces inside their nests, but seal their nests with layers of chewed vegetation and mud over the top of leaf pieces. Depending on how plugs age, they may be reported as "mud/sand," “chewed veg,” or “whole leaf” (see graph in pictures) If they appear to be made from mud or sand, the plugs will often appear darker and dirtier than many other “mud-sand” plugs and will have a mostly smoother surface.

Hole Sizes

Megachile pugnata build nests primarily in column 2 in Bee Atlas blocks (1/4"-5/16"). The also nest in upper column 1 (3/8") holes, and occasionally in lower column 1 (7/16") and lower column 3 (3/16") holes. (see graph in pictures)

Voltinism

Univoltine as far as we can tell, meaning they complete one generation per year in Minnesota.

Activity Period

Megachile pugnata are active in mid-summer. From 2016-2018, most nests were completed in July and August, but a few nests were also completed in September.

References

No information at this time.