Megachile campanulae
Megachile campanulae (Resin bee)
Taxonomy
Megachile campanulae is in the subgenus Chelostomoides 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 exceptions; some Megachile use tree resin and others use chewed vegetation and mud in addition to leaf pieces. Megachile campanulae were common in Bee Atlas blocks and primarily nested in the southern half of the state, in the Prairie Parklands and Eastern Broadleaf Forest provinces. They are commonly found in urban and suburban areas.
Description
Megachile are characterized by large chewing mandibles and a scopa (pollen-collecting hairs) under the females' abdomens. M. campanulae has subtle differences from other Megachile species. They generally appear darker and have less hair; their bodies look a bit more armored and their abdomens, instead of tapering to a point, are parallel sided along their entire length. They resemble large Heriades carinata at first glance, but are not quite as coarsely sculpted and have rounder faces. Megachile campanulae range from 8-11mm long.
Nest Structure
Megachile campanulae are unusual for their genus because they use resin to build their nests instead of leaves. The resin tends to be darker colored, and may have bits of sand, leaves, wood, or debris stuck in it. Resin plugs can be distinguished from other plugs because they are either tacky or rock hard, not papery or flexible. Sometimes if you press lightly with your fingernail you can see an indent left in the newer, tacky plugs, and you may even notice a "piney" smell.
Hole Sizes
Megachile campanulae most frequently nested in lower column 3 (3/16") and upper column 2 (1/4") holes in Bee Atlas blocks. They also sometimes nested in lower column 2 (5/16") and occasionally in larger holes.
Voltinism
Univoltine, meaning they complete one generation per year in Minnesota.
Activity Period
Megachile campanulae are active in mid-summer. From 2016-2018, most nests were completed between the beginning of June and the middle of August in Bee Atlas blocks.
References
No information at this time.
*Volunteer observations gave us a range of dates in which nests were completed. We know the bee completed a nest between the last day a tunnel was observed without a plug and the first day a plug was recorded for that same tunnel. By graphing these date ranges for all nests we can see approximately the time of year most nests were completed.