Megachile relativa

Taxonomy

Megachile relativa is in the subgenus Megachile, within the genus Megachile. 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. Megachile relativa was one of the most common leafcutter bee species in Bee Atlas blocks, particularly in the Laurentian Mixed Forest province.

Description

Megachile are primarily characterized by having large chewing mandibles and scopae (pollen-collecting hairs) under females' abdomens. This species, like many Megachile, is a mostly dark bee with light hair bands across the abdomens of both females and males. Males have unmodified forelegs and look similar to females with extra long antenna and no scopae. Megachile relativa is a medium sized Megachile, not as big as Megachile pugnata, but easily visible to an observer. Bees range from 8-12 mm long. One distinctive characteristic is that the hairs that make up the females' scopae are all a brilliant gold color, best seen when not packed full of pollen. There are even golden hairs on the upper side of the last abdominal segment.

Nest Structure

Like many Megachile, M. relativa use cut pieces of leaves to line their nests. Volunteer monitors report nest plugs either as “chewed leaves” or as “whole leaf or petal pieces”. When “whole leaf” was chosen, the plug was deep in the hole, suggesting that the bees will finish their outer plugs with chewed vegetation if they build to the end of the tunnel. (see graph in pictures)

Hole Sizes

Megachile relativa most frequently uses column 2 holes (1/4-5/16") in Bee Atlas blocks, but also uses column 1 (3/8"-7/16") holes, and occasionally lower column 3 (3/16") holes. (see graph in pictures)

Voltinism

We have collected Megachile relativa emerging in mid summer as well as the following year, implying that this species may sometimes have 1 generation per year and sometimes 2 generations/year in Minnesota.

Activity Period

The first Megachile relativa nests appear to be made between the middle and end of June, with nesting continuing through July and into August. (see graph in pictures)

References

No information at this time.