This is the largest subfamily of Megachilidae and the only subfamily present in Florida. In Florida, it includes four tribes. Nearly all the Megachilinae, with the exception of the Lithurgini, use foreign material from outside the nest to form cells, cell walls, and partitions.
1. Pygidial plate of male present, that of female represented by an apical process or spine; metapleuron with lower half narrow (less than half as wide as upper end and five to six times as long as wide) to linear; outer surfaces of tibiae, except hind tibiae of some males, with coarse tubercles that do not end in bristles..Tribe Lithurgini
Pygidial plate absent; metapleuron with lower half little narrower than upper end (lower one-fourth sometimes considerably narrowed, about twice as long as wide); outer surfaces of tibiae commonly without tubercles, or with tubercles ending in bristles, but sometimes tuberculate as in Lithurgini...2
2. Stigma less than twice as long as broad, inner margin basal to vein r usually little if any longer than width, rarely about 1.5 times width; prestigma commonly short, usually less than twice as broad; claws of female cleft or with an inner tooth; outer surface of hind tibiae usually with abundant simple bristles; body commonly with yellow or white (sometimes red) integumental markings...Tribe Anthidiini
Stigma over twice as long as broad, inner margin basal to vein r longer than width; prestigma much more than twice as long as broad; claws of female usually simple; outer surface of hind tibiae with hairs, these sometimes plumose, but not bristles; body almost always without yellow or white integumental markings...3
3. Arolia absent, at least on hind legs, usually on all legs; preaxilla, below posterolateral angle of scutum, sloping and with small patch of hairs, these as long as those of adjacent sclerites; body nonmetallic or nearly so...Tribe Megachilini
Arolia present; preaxilla, below posterolateral angle of scutum, vertical, smooth and shining or with some hairs, these much shorter than those of adjacent sclerites; body sometimes metallic green, blue, or brassy..Tribe Osmiini