Reprinted with permission from: Mitchell, T.B. 1962 Bees of the Eastern United States. North Carolina Agricultural Experiment Station Technical Bulletin No. 152. |
QUEEN—Length 17-19 mm., breadth of abdomen 8.5-9 mm.; black, legs apically and spurs and tegulae more piceous; wings uniformly and rather deeply infuscated, veins brownish to piceous; pubescence copious and dense but rather short, largely black on head, with a few pale yellowish hairs around antennae and some intermixed pale hairs on vertex medially, otherwise erect and black on vertex, front of face and on cheeks; pubescence yellow and erect on pronotum, anterior margin of scutum, posterior margin of scutellum, tubercles, and mesopleura to bases of legs, black on scutum in large part, and on scutellum medially, propodeal area with more less intermixed light and dark hairs; pubescence pale on basal segments of legs, elongate and largely black on femora, with only few pale hairs at base, short on tibiae and tarsi, the corbicular fringe of quite elongate, blackish hairs, and hind basitarsus thinly covered with pale pruinose hairs which do not obscure the surface; abdominal terga 1 and yellow pubescent, 2 and 3 fulvous, unless faded, 5 and 6 entirely black; clypeus shining, punctures close and rather fine laterally and above, the broad median area with sparse shallow punctures of two different sizes; lab- rum with a basal ridge that is narrowly interrupted medially, this area somewhat excavated, its apical margin broadly rounded, somewhat elevated above the margin on each side, the entire margin fringed apically with rather short yellowish hairs; apex of mandible with two rather deep notches near upper angle, outer surface smooth but rather dull, with some minute and very vague punctures; malar space smooth and shining, without distinct punctures, somewhat shorter than basal width of mandible, about one-fifth length eye; median area of face very finely and closely punctate, punctures becoming somewhat more distinct and more widely separated toward ocelli, space between lateral ocelli and eyes smooth and impunctate or nearly; vertex very finely and densely punctate medially, punctures becoming somewhat more distinct but still close laterally; lateral ocelli sub- equally distant from eyes, margin of vertex and each other; antennal scape somewhat more than half the total length of flagellum, basal segment of flagellum only slightly shorter than 2 and 3 combined, the latter nearly equal; posterior margin of hind basitarsus very slightly curved, base and apex of nearly equal width; tergum 6 smooth and shining, with exceedingly minute, rather sparse punctures, apex rather broadly rounded.
WORKER—Length 8-13 mm., breadth of abdomen 4.5-5.5 mm.; closely resembles queen except in size.
MALE—Length 9.5-13 mm., breadth of abdomen 4.5-5.5 mm.; black, legs and tegulae more piceous, spurs reddish-piceous; wings subhyaline, veins pale testaceous or yellowish to dark brownish; pubescence long and copious, largely yellow on head but with erect and elongate black hairs along margin of eyes, across upper part of face above antennae, just posterior to ocelli, on cheeks above and vertex laterally; posterior two-thirds of scutum and anterior median area of scutellum in part, black pubescent, otherwise thorax with entirely yellow, dense, copious and erect pubescence; pubescence of legs largely pale, quite elongate but with some blackish hairs on mid femora above and on front and mid tibiae posteriorly; abdominal terga 1 and 4 yellow pubescent, 2 and 3 bright fulvous, unless faded, 5-7 black, bordered with yellow laterally; clypeus with fine and close punctures beneath dense pubescence; labrum broadly truncate, shining, with shallow and minute, irregular punctures; mandibles slender, bi-dentate apically, the two teeth nearly equal, outer surface densely yellow pubescent, lower margin fringed with elongate, more or less curled hairs; malar space smooth and shining, with only very obscure, minute punctures at all evident, length about equal to basal width of mandible; median area of face beneath dense pubescence very finely and closely punctate, punctures becoming more distinct and more widely separated toward ocelli, space between lateral ocelli and eyes shining and largely impunctate, but with a few punctures toward the eyes; punctures of vertex fine and densely crowded medially, becoming somewhat more distinct but still very close laterally; lateral ocelli subequally distant from eyes, margin of vertex and each other; basal segment of flagellum very slightly shorter than segment 8, very slightly longer than segment 2; hind tibiae shining and nearly impunctate on the convex outer surface, fringed with elongate pale hairs; hind basitarsus gradually narrowed toward the base which is considerably narrower than the apex; sterna 7 and 8 and genital armature as in impatiens (fig. 133).
DISTRIBUTION—Yukon to Nova Scotia, south to Georgia, May to October. This species is rarely observed south of Pennsylvania.
FLOWER RECORDS — Asciepias, Rubus, Solidago and Vaccinium. Brittain and Newton (1933) record ternarius on Chrysanthemum, Cirsium, Daucus, Narcissus, Pinus (?), Pyrus malus, Rhododendron, Taraxacum and Tulipa.
Extracted from Jonathan Koch, James Strange,Paul Williams.2012. Bumble Bees of the Western United States. A product of the U.S. Forest Service and the Pollinator Partnership
with funding from the National Fish and Wildlife Foundation|
Tri-colored bumble bee
Status: Common in the eastern U.S. but rare in the western U.S.
Select food plant genera: Trifolium, Tanacetum, Chrysothamnus,
Monarda, Achillea, Eriogonum
Tongue Length: Medium
Distribution: Eastern Montana and Black Hills east to New England
Can be confused with B. rufocinctus, B. huntii, and B. bifarius
Thorax and T1 predominantly yellow, with a black band
between the wing bases extending posteriorly in the
middle of the scutellum, T2-3 orange, T4 yellow, T5
black, face round.
Mid leg basitarsus with the distal posterior corner
rounded. Cheek very slightly shorter than broad.
Hair of face and top of the head black with patches
of yellow, or sometimes with black more extensively
intermixed especially for workers, thoracic anterior
band usually yellow without black hairs intermixed
except in some workers, which have the anterior
margin of the black band between the wing bases
always sharply defined, scutellum with yellow patches
entirely divided by a black posteriorly directed triangle,
T2 red, at most with a few black hairs anteriomedially,
T4 yellow, T5 black. Hair length short and even.