Reprinted with permission from: Mitchell, T.B. 1962 Bees of the Eastern United States. North Carolina Agricultural Experiment Station Technical Bulletin No. 152. |
FEMALE—Length 9.5-11.5 mm., breadth of abdomen 4-4.5 mm.; black, the flagellum reddish-piceous beneath, black above; apical tarsal segments becoming brownish, spurs pale yellowish; tegulae piceous; wings subhyaline, veins testaceous to piceous; cheeks slightly broader than eyes; clypeus only very slightly protuberant, its median length about half the distance between eyes below; eyes very slightly convergent below (fig. 85); basal segment of flagellum about twice the length of segment 2; punctures of clypeus contiguous, rather coarse and deep, becoming very fine and densely crowded toward apical margin, those on labrum finer and more distinctly separated; supraclypeal area impunctate medially, becoming densely crowded on each side, lateral areas of face below antennae, rather finely punctate, the punctures well separated, becoming minute and quite sparse above between eyes and ocelli where the surface is shining, the more median punctures below ocelli much more coarse and distinct; vertex finely and densely punctate behind ocelli, somewhat more finely so on each side; cheeks shining, punctures exceedingly minute, becoming somewhat more distinct and deep posteriorly; scutum shining between quite coarse and deep punctures, these rather sparse in median area posteriorly, becoming considerably closer laterally and anteriorly, those on scutellum much finer and quite close but not crowded; punctures of pleura quite deep, close and rather coarse; posterior face of propodeum dull, densely tessellate, the punctures rather coarse and close, but very shallow and obscure, dorsal area quite coarsely reticulate, becoming more striate at each extreme side, lateral faces dull and densely tessellate, punctures quite close but obscure; disc of basal abdominal tergum dull and tessellate across basal two-thirds, with rather coarse but shallow, somewhat separated punctures, these becoming somewhat finer and closer laterally where they nearly reach apical margin, the broad, median, apical area entirely impunctate; tergum 2 basally very finely and rather irregularly punctate, the punctures rather widely separated in general, apical impressed area largely impunctate except toward extreme sides; basal areas of terga 3-5 very finely and closely punctate, becoming almost rugose on the more apical terga, apical impressed areas with exceedingly minute punctures, those on 4 rather close; pygidium elongate-triangular, apex narrowly rounded; pubescence variable, largely black on the head, thorax and abdomen in the dark forms, with light hairs only around tubercles, on propodeum, and on basal abdominal tergum, scopa pale yellowish, the abdominal fasciae fuscous and thus obscure; in the lighter forms there is considerable pale pubescence across front of face and on cheeks laterally and below, the vertex with long fuscous pubescence and some fuscous hairs bordering eyes above; the scutum and scutellum are in large part fuscous pubescent, the scutum being pale pubescent over anterior third, and the pleura above, and entire propodeum pale ochraceous pubescent; the legs are largely black pubescent, but the hind tibial scopa is pale yellow, the hairs densely plumose; the discal pubescence of the abdominal terga is very short, suberect, largely blackish; tergum 2 with a basal whitish fascia, and the apical impressed areas of 2-4 fringed with narrow, whitish fasciae that are slightly interrupted medially; terga 5 and 6 are entirely fuscous pubescent.
MALE—Length 8-9 mm., breadth of abdomen 3-3.5 mm.; black, the clypeus bright yellow, labrum with a basal, median, yellow maculation and mandibles rather obscurely testaceous toward the apex, usually entirely black at base; antennal flagellum testaceous toward apex, usually entirely black at base; antennal flagellum testaceous beneath, piceous above; apical tarsal segments brownish-testaceous, spurs pale yellowish; tegulae dark, brownish-piceous; wings rather whitish-hyaline, veins testaceous to brownish; cheeks much narrower than eyes; clypeus slightly protuberant, its median length about half the distance between eyes below; eyes rather strongly convergent below (fig. 85); basal segment of flagellum slightly longer than pedicel, segment 2 four or five times this length; punctures of clypeus quite close and rather coarse laterally, slightly more distinct medially, but obscure on the yellow surface, those on labrum somewhat deeper and more distinct; supraclypeal area largely impunctate, lateral areas of face below level of antennae distinctly but quite finely and closely punctate, becoming minute and obscure above where the surface is shining between eyes and ocelli, median punctures below ocelli considerably coarser and more distinct; vertex very finely and densely punctate behind ocelli, punctures somewhat more distinct on each side; cheeks shining, punctures exceedingly minute and obscure, but becoming somewhat more deep and distinct toward posterior margin; scutum shining between coarse, deep punctures, these rather sparse over posterior half of disc, becoming finer and closer laterally and anteriorly, those on scutellum slightly finer and rather sparse, the surface shining; pleura quite coarsely, deeply and rather closely punctate; posterior face of propodeum dull and tessellate, punctures shallow, irregularly scattered and obscure, dorsal area dull, becoming rather densely rugose along upper margin, more striate at each extreme side, lateral faces dull, punctures somewhat closer and more distinct; basal abdominal tergum rather dull, punctures rather coarse, shallow and widely separated toward base medially, becoming finer and closer laterally where they nearly reach apical margin, the more apical punctures minute and more widely separated, only the very narrow apical rim entirely impunctate; basal areas of terga 2 and 3 with rather fine, well separated punctures, apical impressed areas practically impunctate, with only a very few, minute, scattered punctures just beyond the fasciae; terga 4 and 5 basally very finely and quite densely punctate, 5 with a quite distinct angle on each side, tergum 6 with a corresponding, more elongate, subtriangular spine; pubescence copious and erect, largely pale yellowish or whitish on head, thorax, basal abdominal tergum and legs; discs of terga 2-6 with short, rather thin, copious, pale pubescence, which does not obscure the surface, some of the more erect hairs appearing darker; tergum 2 with a rather thin, basal, white fascia and a sub- median narrow fascia which fringes the apical impressed area; terga 3 and 4 white fasciate along margin of the impressed area, the apical portion of this area bare and impunetate; terga 5 and 6 largely dark pubescent, but 5 subfasci ate; median length of pygidial plate about equal to the basal width, margins carinate, rather strongly convergent apically to the rather abruptly constricted and truncate apex; sternum 7 and genital armature resembling those in agilie (fig. 84), but sternum 8 narrower at apex.
DISTRIBUTION—Nova Scotia to Georgia and Mississippi, west to Idaho, Arizona and Mexico, May to November.
FLOWER RECORDS—LaBerge (1961) states that rustica is oligolectic on Compositae, preferring species of Solidago and Aster over most of its range. The complete list of plants visited includes also species of Abutiloii, Amphiachyris, Aplopappus, Asciepias, Baccharis, Bidens, Centaurea, Chrysopsis, Cirsium, Cleome, Coreopsis, Cosmos, Epilobiurn, Gaillardia, Grindelia, Heleniurn, Heliant hue, Heliopsis, Hieracium, Lyco pus, MarruhilAm, Melilotus, Mentha, Physostegia, Polyrnentha, Ratibida, Rudbeckia, Silphium, Spiraea, Verbena, Verb esina and Vernonia.
This is a very variable species with respect to the color of pubescence in the female, and in the male also, but to a lesser degree. The variations have some correlation with distribution, with populations in the Eastern United States generally darker than those in the West. A discussion and analysis of this variation is included in Part 3 of LaBerge’s Revision (1961), pp.546-552.