This is a very diverse genus whose species are abundant throughout Florida. All of the species are moderate to large sized bees with black bodies and white (rarely golden) hairs. Females of most subgenera (except Chelostomoides that use resin) cut leaves to line their nests, which may be in the ground or in premade holes in vegetation. The following subgenera (species in parentheses) known from Florida, Acentron (1), Argyropile (2), Callomegachile (1), Chelostomoides (4), Eutricharaea (1), Leptorachis (1), Litomegachile (3), Megachiloides (5), Melanosarus (2), Pseudocentron (1), Pseudomegachile (1), Sayapis (3), and Xanthosarus (2). None of the species are endemic to Florida. Many are widespread in the eastern United States or common along the SE coastal plain. Three species are endemic to the SE from N. Carolina to Florida. Two species are of introduced origin. While most species are widespread and likely occur throughout the state, a few species are geographically restricted to South Florida (M. inimica sayi, M. inimica inimica, M. bahamensis, M. pruina pruina, M. lanata, and M. concinna). Many are polylectic with legumes and composites favorite pollen sources. Most have long flight periods, although members of the subgenus Megachiloides have more restricted flight periods.
S6 with well-dispersed scopal hairs, or, if partly bare, then without bare apical rim behind transverse fringe of short hairs, or (in Argyropile) rim directed upward, or rim narrow and barely recognizable..5
Mandible four-toothed, a well-formed cutting edge in third interspace..3
Mandible less robust, apical tooth not much broader than second or third; gena usually narrower..M. (Leptorachis)
Mandible with cutting edges between teeth, if in second interspace only, then edge complete (in three toothed mandible) or mandible clearly five-toothed, with teeth 4 and 5 about as far apart as 3 and 4...9
Mandible without cutting edges..7
Pubescence with large areas of black or fulvous, forming striking color pattern ..8
Mandibular carinae minutely roughened, sometimes dull..M. (Callomegachile)
Mandibular carinae shining and smooth..M. (Pseudomegachile)
S6 without apical rim, or, if rim present, than directed posteriorly and usually inconspicuous..10
Mandible four- or five-toothed, with cutting edges in third and usually second interspaces, or rarely in second only..11
Metasomal sterna with white hair fasciae absent or broadly interrupted medially..12
Mandible four or five-toothed, but if four-toothed, then upper tooth rounded, truncate, or incised (sometimes only minutely) and thus approaching the five-toothed condition...M. (Xanthosarus
T6 usually concave in profile; mandible with second tooth acute, a small beveled cutting edge in second interspace..M. (Litomegachile), also includes M. addenda (Xanthosarus).
Middle tibial spur present, articulated to the tibia, about as long as apical tibial width, or, if absent, (as in some species of Xanthosarus), then middle basitarsus modified and swollen..5
Middle tibial spur absent or represented by prong immovably fused to tibia...3
Middle tibia without such a process..4
Punctures of scutum usually well separated, but, if close, then individually distinguishable..M. (Melanosarus)
S4 exposed, thus four exposed sterna, punctation and vestiture of S4 similar to those of S3..6
S8 without marginal hairs, but discal hairs sometimes extending laterally beyond margin; body usually megachiliform, usually without a striking color pattern..8
T6 with carina strong, , strongly dentate or denticulate, or sometimes scarcely undulate..M. (Pseudomegachile)
Metasoma less than twice as long as wide..9
Carina of T6 commonly crenulate, median part emarginate or sometimes irregular but not produced..10
Mandible three-toothed..12
Front coxa hairy, without red bristles; front tarsus simple, dark colored (Neartic)..M. (Argyropile)
Morphological apical margin of T6 with four small but distinct teeth..M. (Litomegachile)