Reprinted with permission of the American Entomological Society from:
LaBerge, W. E. 1980. A revision of the bees of the genus Andrena of the Western Hemisphere. Part X. Subgenus Andrena. Transactions of the American Entomological Society 106: 395-526.
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This wide-spread, moderately-sized bee is difficult to characterize because of an unusual amount of variation, especially in color of the vestiture; Both sexes of frigida lack basal mandibular teeth, have relatively short malar spaces, short vertices, dulled scutella, and dulled, almost impunctate terga; The clypeus in both sexes, but especially the female, is finely shagreened and provided with small, crowded, round punctures; The head of the female is broad and the male has the first flagellar segment one and one-half to two times as long as the second segment.
FEMALE. MEASUREMENTS AND RATIOS. — N = 20; length, 9-12 mm; width, 2.5-4.0 mm; wing length, M = 4.45±0.279 mm; FL/FW, M = 0.89±0.006; FOVL/FOVW, M = 3.10±0.062.
INTEGUMENTAL COLOR. — Black except as follows: mandible with apical third or more rufescent; flagellar segments 2 to 10 dark brown to dark reddish-brown below; tegula dark, translucent reddish-brown to piceous; wing membranes hyaline, only slightly infumate, veins dark brown; distitarsi dark rufescent to dark brown; tibial spurs testaceous to reddish-brown; terga 1-4 with apical areas usually slightly translucent, brown to reddish-brown, basal areas usually with extremely slight metallic reflections; sterna 2-5 often rufescent in part, apical areas hyaline.
STRUCTURE. — Antennal scape length equals first three flagellar segments to first two and one-half segments; flagellar segment 1 equal in length to following two and one-half segments; segment 2 slightly shorter than segment 3 and broader than long; median segments as long as broad or slightly longer; Eyes each about three and three-fourths times as long as broad, inner margins parallel to converging slightly towards mandibles; Mandibles short, when closed surpassing midlabrum by about one-fifth mandible length; without inferior basal angle or tooth; Malar space short, minimum length equals about one-fourth basal mandibular width or less; Galea pointed, outer-apical margin slightly concave, surface dull, finely shagreened with minute scattered punctures; Maxillary palpus exceeding galea by last two segments or slightly less, segmental ratio about as 1.0:1.0:0.9:0.6:0.6:0.6; Labial palpus short, segmental ratio about as 1.0:0.5:0.4:0.5; Labral process small, entire to slightly emarginate, shiny; labrum below process with weak median crista, otherwise flat, shiny, impunctate except immediately below process; Clypeus broad, evenly rounded from side to side, with small round punctures separated largely by half a puncture width, surface usually dulled by fine shagreening; median impunctate line, if present, narrow and ephemeral posteriorly; Supraclypeal area dulled by minute punctures; Face above antennal fossae dulled by fine, parallel, longitudinal rugulae, scattered punctures and fine tessellation; Facial fovea large, shallow, extending to below a line at lower margins antennal fossae, separated from lateral ocellus by about half an ocellar diameter; Vertex above lateral ocelli equals less than one ocellar diameter (about as 6 or 7:8), dull, tessellate; Genal area broad, in profile about one and one-third times as broad as eye; surface dulled by fine reticular shagreening and minute punctures separated mostly by one to two or more puncture widths.
Pronotum with distinct ridge but somewhat rounded or blunt, surface dulled by fine reticular shagreening; Mesoscutum uniformly opaque, dulled by fine tessellation, punctures obscure; scutellum and metascutum similar; Propodeum with dorsal enclosure finely tessellate, slightly roughened or with short rugulae at base; surfaces outside of enclosure tessellate, punctures obscure; Mesepisternum opaque, finely tessellate, punctures minute, shallow, obscure, separated largely by one to two puncture widths.
Metasomal terga 1-5 dulled to slightly shiny (especially apical areas), with fine reticular shagreening, basal areas with minute scattered obscure punctures separated largely by 2 to 4 puncture widths or more; Pygidial plate V-shaped with rounded apex, with internal raised triangular area present unless worn; Sterna 2-5 dulled by coarse reticular shagreening, basal areas with minute but distinct punctures separated by one to two puncture widths (sparser basally) in apical half of each basal area.
VESTITURE. — Pale specimens with hairs white to dark rufescent except as follows: facial fovea dark brown; face along inner margins compound eyes and vertex dark brown to black; terga 5 and 6 with some brown; outer surfaces middle and fore tibiae brown; inner surfaces basitarsi yellow to orange; Dark specimens with pale ochraceous to dark rufescent hairs except as follows: head entirely black to dark brown except a few long pale hairs of vertex and/or face surrounding antennal bases; mesoscutum with a few brown hairs posteromedially mixed with the pale; thoracic pleurae dark brown to black at least below; propodeum dark brown laterally and posteriorly; terga 3-6 dark brown to black; sterna dark brown; leg hairs dark brown except at least anterior tibial scopal hairs and hind femoral hairs; All transitional stages of melanism occur between these two extremes; Body vestiture generally long; on clypeus dense and plumose, hiding surface in fresh specimens; terga 1-4 with apical areas without bands, surfaces with scattered, extremely long, weak hairs giving a linty appearance, especially in pale specimens; Propodeal corbiculum complete with few or no internal hairs; tibial scopal hairs short, dense, along posterior margin about half as long as median tibial width or longer, much longer along anterior margin; trochanteral flocculus complete.
MALE. MEASUREMENTS AND RATIOS. — N = 20; length, 8-10 mm; width, 1.5-2.5 mm; wing length, 3.96±0.224 mm; FL/FW, M = 0.91±0.008; FS1/FS2, M = 1.83±0.033.
INTEGUMENTAL COLOR. — Black except as follows: mandible with apical third or less rufescent; flagellum below dark brown to black; tegula piceous; wing membranes hyaline, slightly infumate, veins dark brown; distitarsi dark brown or black to dark rufescent; tibial spurs testaceous; terga 1-5 with apical areas slightly translucent; sterna 2-5 dark brown to dark rufescent.
STRUCTURE. — Antennae moderately long, reaching mid-scutellum in repose; scape length equals first one and one-half to one and three-fourths flagellar segments; flagellar segment 1 long, usually equal to one and one-half times second segment or more, segment 2 as long as broad or slightly longer; median segments about one and one-third times as long as broad; Eyes narrow, each slightly less than three and one-half times as long as broad, inner margins converging slightly towards mandibles; Mandibles slightly decussate, when closed extending beyond midlabrum by about one-third mandible length; without basal teeth; Malar area short, minimum length equals one-fourth basal mandibular width; Galea as in female; Maxillary palpus as in female but segmental ratio about as 1.0:1.0:1.0:0.7:0.7:0.7; Labial palpus as in female but ratio about as 1.0:0.4:0.4:0.4; Labral process as in female, usually not emarginate, quite small; Clypeus relatively flat, with small, densely crowded punctures and weak shagreening dulling surface, median impunctate line usually absent, weak and incomplete when present; Supraclypeal area, face above antennal fossae and vertex as in female; Genal area in profile one and one-half to two times as broad as eye; angulate posteriorly; sculptured as in female.
Pronotum with dorsoventral ridge sharp; depressed area behind ridge shiny, without distinct rugulae (a few indistinct, weak, incomplete wrinkles may be present); surface anterior to ridge dulled by fine dense tessellation; Mesoscutum, scutellum, metascutum and mesepisterna as in female; Propodeum as in female but enclosure usually roughened at extreme base or in basal half.
Metasomal terga sculptured as in female; Tergum 7 with extremely narrow, pointed, shiny, pseudopygidial area; Sterna 2-5 with basal areas with small punctures scattered throughout, surfaces moderately shiny, weakly shagreened; Sternum 6 flat, apical margin extremely shallowly concave.
Terminalia as in Figs; 17 to 21; note sternum 7 with apex entire, pointed, and sternum 8 slightly emarginate.
VESTITURE. — Generally white to pale ochraceous (rarely dark yellow) except as follows: vertex and face alongside of compound eyes with black hairs; propodeum with black and pale mixed except dorsally; inner surfaces tarsi yellow; Dark specimens (rarer than in female) may have head entirely black, thoracic pleurae entirely black, terga 3-5 with dark and pale hairs mixed and leg hairs in part dark; All intergrades occur between normal pale and dark individuals but males tend to be paler than females; Hair in general long, weak; terga 2-5 without apical fasciae, basal area hairs long, weak, not aiding surfaces; sterna 2-5 with subapical fimbriae of short, pale, straight, suberect hairs usually one hair thickness; Sternum 6 without conspicuous apical tuft, hairs short.
Reprinted with permission from: Mitchell, T.B. 1960. Bees of the Eastern United States. North Carolina Agricultural Experiment Station Technical Bulletin No. 141.
FEMALE — Length 11 mm.; length and breadth of face subequal; clypeus rather flat, broader than long, finely and quite closely punctate; facial foveae broad, fuscous tomentose; space between margin of vertex and lateral ocelli subequal to their diameter; cheeks slightly broader than eyes, minutely punctate; basal segment of flagellum slightly exceeding 2nd and 3rd combined; process of labrum subtriangular, truncate at tip; mandibles of ordinary length, with a small inner tooth; pubescence of head quite long and white in general, but fuscous around eyes and between foveae and antennae; thoracic integument dull and tessellate. very minutely and obscurely punctate, pubescence entirely greyish-white; enclosure of propodeum smooth; propodeal corbicula well developed, fringed anteriorly; tibial scopa short, hairs simple; trochanteral floccus well developed; fore and hind basitarsi slightly narrower than their tibiae, the mid basitarsi nearly as broad as the mid tibiae; 2nd submarginal cell much shorter than 3rd, receiving 1st recurrent vein near the apex; abdominal terga rather dull, very minutely, obscurely, and rather sparsely punctate; apical depressed margins occupying about one-third of the disc, concolorous with disc, abdominal pubescence long, thin and erect, greyish-white, slightly more dense along apical margins of terga, to form inconspicuous fasciae.
MALE — Length 8 mm.; length and breadth of face subequal; clypeus flat, slightly broader than long, finely, closely, and uniformly punctate; space between margin of vertex and lateral ocelli slightly exceeding their diameter; cheeks very broad and flat, subangulate, angle opposite middle of eye (as in clarkella, fig. 21); malar space distinct but short; basal segment of flagellum slightly shorter than 2nd and 3rd combined; process of labrum subtriangular, the apex truncate and slightly emarginate, mandibles slender, slightly flexed, tips overlapping about one-fourth; pubescence of head long, dense and erect, white, intermixed with fuscous around eyes, cheeks and ocelli; thoracic integument dull, densely tessellate, punctures barely visible; enclosure smooth; pubescence long and quite dense, white intermixed with fuscous above; basitarsi slender and elongate, much narrower than their respective tibiae; 2nd submarginal cell much shorter than 3rd, receiving 1st recurrent vein beyond middle; abdominal terga smooth, dull, apical margins only slightly depressed, punctures exceedingly minute and obscure, pubescence rather long, thin and erect, fasciae not well developed; apical portion of sternum 8 quite narrow and elongate, with a low, dorsal, subapical ridge, tip beyond this slightly rounded and very slightly incised; penis valves broadly expanded basally, deeply excavated beneath this expansion, gonocoxites quite narrow and elongate, gonocoxal lobes strongly produced and broadly rounded.
DISTRIBUTION — Alaska to Nova Scotia, and in the United States from Minnesota to the New England states, south to Virginia; March to June.
FLOWER RECORDS — Brittain and Newton (1934) record frigida on Cornus, Prunus and Salix.