Reprinted with permission of the American Entomological Society from:
LaBerge, W. E. 1977. A revision of the bees of the genus Andrena of the Western Hemisphere. Part VIII. Subgenera Thysandrena, Dasyandrena, Psammandrena, Rhacandrena, Euandrena, Oxyandrena. Transactions of the American Entomological Society 103: 1-144.
Please report text errors to: leah at discoverlife dot org.
This widespread species is one of our most common species of the subgenus Thysandrena. It is very similar morphologically to candida but can be differentiated from that species by the complete lack of violaceous or metallic reflections of the integument. A few dark specimens of candida are only feebly metallic and these are almost impossible to distinguish from w-scripta. In the eastern part of its range the females of w-scripta are easily confused with those of bisalicis but can be recognized by the fine sculpture of the terga which is transversely reticulate in w-scripta and distinctly tessellate and not at all transverse in bisalicis.
FEMALE. MEASUREMENTS AND RATIOS. — N = 20; length, 8-11 mm; width, 2.5-3.0 mm; wing length, M = 3.08 ± 0.187 mm; FL/FW, M = 0.94 ± 0.006; FOVL/FOVW, M = 3.17 ± 0.054.
INTEGUMENTAL COLOR. — Black except as follows: mandible with apical third rufescent; flagellum below reddish-brown to black (usually dark brown); tegula slightly translucent, dark; wing membranes hyaline, slightly yellowed apically, veins dark reddish-brown to black; terga 2-5 with apical areas often slightly translucent; tarsi dark reddish-brown to black.
STRUCTURE. — Antennal scape length equals first three and one-half to almost four flagellar segments; flagellar segments as in candida. Eyes each about four times as long as broad or slightly less, inner margins converging slightly towards mandibles. Malar space, mandibles and galea as in medionitens. Maxillary palpus as in medionitens but segmental ratio about as 1.0;1.0:0.9;0.9:0.7:0.7. Labial palpus as in medionitens but ratio about as 1.0:0.7:0.6:0.7. Labrum as in candida. Clypeus as in candida but usually somewhat flattened medially, impunctate midline usually not evident, punctures irregular in size but small. Supraclypeal area as in candida. Genal area as in candida but often shiny, shagreened only posteriorly (entirely shagreened in most eastern specimens). Vertex and face above antennal fossae as in candida. Facial fovea as in candida and medionitens.
Pronotum as in candida. Mesoscutum shiny except shagreened peripherally to dulled by fine tessellation or shagreening throughout; punctures sparse posteromedially. Scutellum, propodeum and mesepisternum as in candida. Wings as in medionitens.
Metasomal terga, sterna and pygidial plate as in medionitens and candida. Tergal fine sculpture consisting of fine, transversely reticular shagreening at least laterally on discs, occasionally extremely finely tessellate medially.
VESTITURE. — As in candida but often pale ochraceous to yellow especially in northern and eastern parts of the range.
MALE. MEASUREMENTS AND RATIOS. — N = 20; length, 7-10 mm; width, 1.5-2.5 mm; wing length, M = 2.87 ± 0.234 mm; FL/FW, M = 0.97 ± 0.009; FS1/FS2, M = 1.18 ± 0.029.
INTEGUMENTAL COLOR. — As in candida but lacking metallic or violaceous reflections and clypeus not showing yellow in any specimens before me.
STRUCTURE. — Antennae short, in repose reaching metascutum; scape length equals first two to two and one-third flagellar segments; flagellar segment 1 usually slightly longer than segment 2 and equal to segment 3, segments distinctly longer than broad except occasionally 2 shorter. Eyes, malar space, mandible and galea as in candida. Maxillary palpus as in medionitens but segmental ratio about as 1.0:0.9:0.9:0.7:0.6:0.6. Labial palpus as in medionitens but ratio about as 1.0:0.7:0.7:0.7. Labral process as in candida. Clypeus as in female but punctures smaller. Supraclypeal area, genal area, vertex and face as in female.
Thoracic sculpturing as in female but propodeum with dorsal enclosure often minutely roughened mediobasally.
Metasomal terga as in female. Sterna with sparse punctures basally, as, in medionitens. Sternum 6 flat, emarginate apicomedially. Terminalia as T in Figures 27-31.
VESTITURE. — Generally as in candida but pale hairs often yellowish especially in northern and eastern parts of the range and less often largely black; sterna 2-5 with well-formed, pale, apical fimbriae of moderately long, curved hairs. Sternum 6 normally hairy, not densely so.
REMARKS. — Andrena w-scripta is variable in details of sculpture and in the color of the vestiture, but not markedly so. Specimens from Washington and British Columbia east to the Atlantic seaboard have the apical fasciae of terga 2-4 more broadly interrupted medially than those from Oregon, California, Nevada, Utah and Colorado. These northern and eastern forms could be considered as a geographical race under the subspecific epithet of lata Viereck. However, such individuals do occur in the west, south into Oregon, northern California, Wyoming and northern Colorado and the western, typical form, has been collected as far east as North Dakota. There exists a continuous series of intergrades scattered throughout the northwestern states and southwestern Canada, so that no clear stepped dine occurs. Under these circumstances, it seems more practical not to recognize an eastern subspecies.
It seems likely that w-scripta is bivoltine, as is candida, considering the long period of time during which it can be taken. It is, perhaps univoltine in the east and north, and bivoltine only in the southwest.
Reprinted with permission from: Mitchell, T.B. 1960. Bees of the Eastern United States. North Carolina Agricultural Experiment Station Technical Bulletin No. 141.
Description based on the synonymous name: Andrena lata
FEMALE. — Length 9 mm.; clypeus convex, projecting about one-half below suborbital line, rather dull, punctures fine and well separated medially, becoming closer laterally, without a median impunctate line; facial foveae rather broad above, occupying about two-thirds of area between eyes and lateral ocelli, (as in bisalicis, fig. 43) covered with whitish tomentum; space between margin of vertex and lateral ocelli very slightly greater than their diameter; cheeks broader than eyes, rounded posteriorly, somewhat shining, very minutely, obscurely and rather closely punctate; malar space very short; basal segment of flagellum subequal to 2nd and 3rd combined; process of labrum much broader than long, subtriangular, apex narrowly truncate; pubescence of head and thorax whitish; thoracic integument dull and tessellate, punctures of scutum shallow and rather obscure, well separated but not sparse anteriorly, becoming quite sparse posteriorly, and sparse and minute on scutellum; pleura more densely tessellate, punctures inevident; enclosure of propodeum dull, densely tessellate; propodeal corbicula rather short, anterior fringe poorly developed; trochanteral floccus rather well developed, whitish; tibial scopa dense, hairs rather long, mostly simple or very obscurely plumose, pale ochraceous, becoming somewhat brownish posteriorly, hind tibiae rather slender and elongate; all basitarsi slightly narrower than their respective tibiae; basal segments of legs pale pubescent, becoming brownish pubescent on the tarsi; 2nd submarginal cell considerably shorter than 3rd, receiving 1st recurrent at middle; abdominal terga somewhat shining, very faintly greenish, microscopically tessellate, impunctate except for some exceedingly minute and obscure punctures laterally, apical margins rather narrowly but distinctly depressed, these areas becoming reddish-hyaline toward rims, discal pubescence exceedingly short and obscure, entirely pale, segments subfasciate toward sides, the fasciae loose, pale ochraceous, tergum 5 with a quite dense, apical, brownish fimbria.
MALE. — Length 7 mm.; clypeus rather markedly convex, projecting about one-third below suborbital line, rather smooth and shining, punctures quite deep, distinct and rather fine, close laterally, more distinctly separated medially beneath rather dense, whitish pubescence; space between margin of vertex and lateral ocelli subequal to their diameter; cheeks slightly broader than eyes, rather flat, rounded posteriorly, somewhat shining, punctures exceedingly obscure; malar space very short; basal segment of flagellum longer than 2nd segment, subequal to 3rd; process of labrum short and rather broad, apical margin rather broadly emarginate; mandibles of moderate length, with a small but distinct inner subapical tooth, over-lapping about one-third; pubescence of head, thorax and legs dull white, faintly yellowish; thoracic integument dull, tessellate, punctures of scutum very fine and obscure, well separated anteriorly, becoming quite sparse in center posteriorly, those on scutellum exceedingly minute, scattered and obscure; pleura dull, rather densely tessellate, punctures inevident; enclosure of propodeum dull, densely tessellate; all basitarsi slender and elongate, considerably narrower than their respective tibiae; 2nd submarginal cell considerably shorter than 3rd, receiving 1st recurrent near middle; abdominal terga somewhat shining, faintly greenish, with rather sparse and exceedingly minute punctures, apical margins rather narrowly but distinctly depressed, these areas becoming reddish-hyaline toward rims, pubescence short, erect, pale, apical fasciae barely evident at extreme sides; sternum 7 produced medially, this area deeply emarginate, resulting in a pair of narrow, elongate lobes; apical portion of sternum 8 narrow and elongate, the sides nearly parallel, with a low but distinct, median, ventral protuberance, quite densely pubescent from this to near the apex, which is slightly incised medially; penis valves slightly expanded basally, but not excavated, gonocoxites slightly dilated apically, gonocoxal lobes slightly produced, narrowly rounded.
DISTRIBUTION. — Minnesota to Nova Scotia and the New England states, south to North Carolina and Georgia; March to July.
FLOWER RECORDS. — Brassica, Hydrangea, Potentilla, Prunus and Rubus. Recorded by Brittain and Newton (1934) on Pyrus malus.
Both lata F and vulgaris M were described in the same paper (Viereck 1922) but the relationship was not suggested. The type of lata was deposited in the Boston Society of Natural History, and is now in the collection of the Museum of Comparative Zoology at Harvard University. According to Viereck's paper, the type of vulgaris was also on deposit in the Boston Society, but it could not be found in that collection. A specimen labeled "Type" in Viereck's handwriting has been found in the Philadelphia Academy of Science, however, and it agrees with the male of lata as it is now interpreted.