Bellflower Resin Bee

M. campanulae are medium-sized bees. Anatomically, they have a head, a middle section called a mesosoma, and a posterior section called a metasoma. The mesosoma is formed by fusion of the first abdominal segment or propodeum with the thorax. They have both compound eyes and simple eyes (ocelli), similar to many other insects. The mandibles in these resin gathering bees are characteristically lacking cutting edges found in the closely related leafcutters. The males are smaller than the females. The body segments are covered in various aspects with fine short hair called pubescence. The hairs are of varying length, texture, and color on different aspects of the male and female bees. Morphologically, M. campanulae most resemble Megachile angelarum. There are also marked similarities in appearance between M. campanulae and M. exilis. The males of M. exilis have characteristically dilated and hollowed out front tarsal leg segments. The tarsi in M. campanulae are not modified and are otherwise unremarkable.

Females. M. campanulae females measure 10–12 millimeters (0.39–0.47 in) in length. Although they resemble M. angelarum, the white banding (fascia) at the apex of the 5th tergal segment found on M. angelarum is absent in M. campanulae. Females can also be recognized by parallel sided metasoma.

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The range of M. campanulae covers a broad expanse of the eastern North American continent. They are native to southern Ontario. The range extends from this southeastern Canadian province, through the New England states to Florida. The range extends west, as far as Minnesota, Nebraska and Texas. A few reports of sightings further west are noted, including presence in Colorado and Montana.

As a member of the subgenus Chelostomoides, M. campanulae are mason bees. This means that they use plant resins, mud, and pebbles for nest construction. Typically the females build small nests in pre-existing holes in trees, fences, or plant stems. They will also nest in artificial "nest-traps" or "bee-blocks." They build the nests as a long single column of cells, along a tube. The deepest cells are constructed first, at which point the female lays a single egg sequentially in each cell. The cells are partitioned and sealed using some combination of the construction materials described above. Pollen, sometimes mixed with nectar, provisioned in the cell will nourish the larvae when hatched. The bees are polylectic, meaning the larvae are fed from a variety of pollen sources. Subsequently, after a few stages of molting, the larvae spin cocoons and pupate. They will overwinter as pupae. After several months, the bees will emerge in the adult form. Males typically emerge in advance of females. They will die shortly after mating. The female bees survive for another few weeks, during which time they build new nests and gather provisions. Adult bees are active from April to September throughout most of the range. In Florida, that have been collected as early as February and as late as November. …