 © Copyright source/photographer · 9 Bombus bimaculatus, female, face 2012-07-25-12.32.14 |
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Gives a common name of Two-Spotted Bumble Bee.
QUEEN Length 17-22 mm., breadth of abdomen 8.5-10 mm.; black, apical tarsal segments becoming more piceous, spurs reddish-piceous, tegulae black; wings lightly infuscated, veins brownish to piceous; pubescence copious and dense but rather short, largely black on head but with some conspicuous yellow pubescence on vertex medially just posterior to a dense fringe of black hairs; thorax largely yellow pubescent, with only a rather small, median posterior area of black hairs and some dark hairs on lateral faces of propodeum below; pubescence of legs largely black or fuscous, with a few pale hairs in posterior fringes of femora, corbicular fringe composed of elongate, black hairs; basal abdominal tergum yellow pubescent and tergum with a small amount of yellow toward base across the median third, abdomen otherwise densely black pubescent; clypeus smooth and shining, with rather close, fine, irregular punctures along the narrow lateral and upper margins, the broad, median, apical area nearly impunctate; labrum quite broadly truncate, with a basal ridge which is interrupted medially, apical margin fringed with golden hairs, slightly rounded medially and or each side, with a low emargination separating them; apex of mandible with a pair of low, obscure notches toward upper angle, lower angle very slightly emarginate, outer face rather smooth, only obscurely punctate; malar space smooth and shining, median length about equal to basal width of mandible, about one fourth length of eye; median area of face very finely and closely punctate, punctures becoming somewhat more distinct and separate toward ocelli, surface largely smooth and impunctate between ocelli and eyes; punctures minute and densely crowded on vertex medially, very fine and close even laterally; antennal scape slightly more than half total length of flagellum, basal segment of flagellum only slightly shorter than segments 2 and 3 combined, 3 somewhat longer than 2; posterior margin of hind basitarsus nearly parallel with anterior margin; tergum 6 narrowly rounded apically, with a low, obscure, median ridge apically, surface shining and minutely punctate.
WORKER Length 11-16 mm., breadth of abdomen 5-6.5 mm.; very similar to queen except in size.
MALE Length 13-14.5 mm., breadth of abdomen 6-6.5 mm.; black, apical tarsal segments somewhat more piceous, mid and hind spurs reddish; tegulae becoming obscurely yellowish-hyaline along outer margin; wings lightly infuscated, veins testaceous to piceous; pubescence long, copious and dense, black and erect below and above antennae and just above ocelli, but vertex with dense yellow pubescence along posterior margin; cheeks below with elongate yellowish pubescence, this becoming darker toward vertex; clypeus with considerable short, yellowish pubescence, with scattered, elongate black hairs; thorax largely yellow pubescent, with only a very small, median, posterior area of obscure dark pubescence; legs with considerable pale pubescence basally but with largely fuscous fringes on tibiae, outer surface of basitarsi more or less pale pubescent, the lower surface reddish- brown; basal abdominal tergum and median basal area of tergum 2 with yellow pubescence, the following segments with varying amounts of black and yellow, sometimes entirely black, sometimes largely yellow on 4 or 5 and tergum 2 in some specimens entirely yellow; clypeus very finely and rather closely punctate but shining beneath quite dense pubescence; labrum shining, truncate apically with only a few obscure, minute punctures medially toward base, apical half more closely but minutely punctate; mandibles very small and slender, bidentate apically, outer surface densely ochraceous tomentose, apical margin with a fringe of elongate, testaceous hairs; malar space smooth and shining, only very minutely and obscurely punctate, its median length somewhat greater than basal width of mandible, about one-fourth length of eye; face very finely and closely punctate medially beneath quite dense pubescence, becoming more coarsely and sparsely punctate toward ocelli, space between lateral ocelli and eyes shining and largely impunctate; vertex very densely and rather finely punctate medially, becoming more minute and obscure but still quite close laterally; basal segment of flagellum slightly longer than segment 2, slightly shorter than 3; lower surface of hind tibiae somewhat convex, shining and sparsely punctate, posterior fringe of elongate hairs, the basitarsus nearly parallel-sided; terga 7 and 8 and genital armature as in impatiens (fig. 133).
DISTRIBUTION Ontario to Maine, south to Mississippi and Florida, March to September, February in Florida.
FLOWER RECORDS Batodendron, Cirsium, Halesics, Hydrangea, Hypericum, hex, Itea, Kalmia, Malus, Melilotus, Pentstemon, Prunus, Rhododendron, Rosa, Rubus, Solidago, Stachys, Vaccinium and Vicia. Robertson (1929) records bimaculatus also on Amelanchier, Blephilia, Collinsia, Caulophyllum, Cephalanthus, Dentaria, Dicentra, Geranium, Helianthus, Hydrophyllum, Mertensia, Monarda, Nepeta, Phlox, Polemonium, Ribes, Seymeria, Triosteum, Trifolum, Uvularia and Verbena.
Reprinted from: LaBerge, W.E., and Webb, M.C. 1962. The Bumblebees of Nebraska. University of Nebraska College of Agriculture-Agricultural Experiment Station, Research Bulletin No. 205
This species is eastern in distribution and is found in relatively
small numbers in the eastern fourth of. Nebraska. It is very similar to B. griseocollis in general coloration, but can be told from griseocollis by the longer malar space in both sexes of bimaculatus.
Females: Head with hairs black, a small amount of yellow pile may
be present on vertex; thorax with sides with yellow pile, dorsum with
yellow pile (occasionally a small posteromedian patch of black hairs on mesoscutum); terga I with yellow pile; tergum 2 with black pile with two large basomedial patches of yellow; terga 3-6 with black pile; legs with hairs black; malar space distinctly longer than broad, head elongate in outline; ocelli placed on supraorbital line.
Males: Head with hairs predominantly black but often cinereous or
white mixed with black on clypeus and surrounding antennal fossae
and vertex usually with some yellow; thorax with pile entirely yellow;
tergum I with yellow pile; tergum 2 with yellow pile or black laterally and often along apical margin and yellow basomedially; rarely with a few brownish yellow hairs scattered among the black on terga 3 and 4; terga 3-7 with black pile; legs with black hairs; hind tibiae with outer surfaces obscured by short suberect hairs and minute punctures; malar space distinctly longer than broad; first flagellar segment longer than second and subequal to third.
Locality Records. (Fig. 4) CASS: Louisville; South Bend; Union.
DIXON: Maskell. DODGE: Fremont. DOUGLAS: Omaha. LANCASTER:
Lincoln. OTOE: Nebraska City. SARPY: Childs Point.
Dates Collected. Queens have been taken as early as April 14 (Lincoln)
and as late as May 29 (Nebraska City). Workers have been taken
as early as May 31 (Fremont) and as late as July 31 (Omaha). Males
have been taken as early as .July 2 (Omaha) and as late as August 15
(Omaha).
Extracted from: Laverty T.M., & Harder L.D., (1988). The Bumble Bees of Eastern Canada. Can. Ent. 120: 965-987.
Description. Queen body size medium; worker and male small to medium. Head moderately elongate; malar space slightly longer than wide. Tongue length medium. Color as in Figure 6. Some specimens have the yellow pile on T2 reduced to the medial proximal third of the segment, or rarely T2 largely yellow. Males occasionally have yellow pile on T4 and T5.
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