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Bombus appositus Cresson, 1878
Life   Insecta   Hymenoptera   Apoidea   Apidae   Bombus
Subgenus: Subterraneobombus

Bombus appositus FEM
© Copyright Laurence Packer 2014 · 7
Bombus appositus FEM

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IDnature guides

    Williams, Paul H., Robbin W. Thorp, Leif L. Richardson, and Sheila R. Colla. Bumble Bees of North America: An Identification Guide. Princeton University Press, 2014. http://www.jstor.org/stable/j.ctt6wpzr9.

    - has the best modern color guides for identification of both sexes, microscopic identification characters, range and natural history notes.

    Gives the common name of White-Shouldered Bumble Bee.

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Bombus appositus MALE mm -. f
© Copyright Laurence Packer 2014 · 7
Bombus appositus MALE mm -. f
Bombus appositus, Diane Wilson
Diane Wilson · 5
Bombus appositus, Diane Wilson

Bombus appositus
© Copyright John Ascher, 2006-2014 · 4
Bombus appositus
Bombus appositus
© Copyright John Ascher, 2006-2014 · 4
Bombus appositus

Bombus appositus
© Copyright John Ascher, 2006-2014 · 4
Bombus appositus
Bombus appositus
Diane Wilson · 1
Bombus appositus

Bombus appositus
Diane Wilson · 1
Bombus appositus
Bombus appositus
Diane Wilson · 1
Bombus appositus

Bombus appositus, female
Diane Wilson · 1
Bombus appositus, female
Bombus appositus, Barcode of Life Data Systems
Barcode of Life Data Systems · 1
Bombus appositus, Barcode of Life Data Systems

Bombus appositus
Adalbert Goertz · 1
Bombus appositus
Bombus appositus
Adalbert Goertz · 1
Bombus appositus

UGCA195807 01.worker_front.320.jpg
© Photographer/source
worker front
UGCA195807 02.worker_front_top.320.jpg
© Photographer/source
worker front top

UGCA195807 03.worker_top.320.jpg
© Photographer/source
worker top
UGCA195807 04.worker_side.320.jpg
© Photographer/source
worker side

UGCA195807 05.worker_rear.320.jpg
© Photographer/source
worker rear
UGCA195807 06.worker_rear_tip.320.jpg
© Photographer/source
worker rear tip

UGCA196020 01.male_front.320.jpg
© Photographer/source
male front
UGCA196020 02.male_front_top.320.jpg
© Photographer/source
male front top

UGCA196020 03.male_top.320.jpg
© Photographer/source
male top
UGCA196020 04.male_side.320.jpg
© Photographer/source
male side

UGCA196020 05.male_rear.320.jpg
© Photographer/source
male rear
UGCA196020 06.male_rear_tip.320.jpg
© Photographer/source
male rear tip
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

White-shouldered bumble bee

Status: Common

Select food plant genera: Cirsium, Delphinium, Linaria, Trifolium, Geranium, Penstemon

Tongue Length: Long

Distribution: Abundant in higher elevations in the Cascades, Sierra Nevada, intermountain West and Rocky Mountains; less abundant in the coastal plains of Oregon and Washington

Can be confused with B. fervidus

Thorax anterior to black band between wing bases predominately white, scutellum yellow or occasionally white and T1-5 predominantly yellow or sometimes orange-brown, face long.

Mid leg basitarsus with the distal posterior corner sharply pointed (may be hidden by hair). Cheek longer than broad. Hair of the face and top of head predominately white or occasionally yellow. On the side of the thorax, the lower anterior surface with predominantly black hair, corbicular fringes black. Hair length short and even.

Extracted from: Milliron H.E., (1973). A Monograph of the Western Hemisphere Bumblebees (Hymenoptera: Apidae; Bombinae). The Entomological Society of Canada, No. 89.

Description. Queen. Length, 22.5 mm; width at wing bases, 9.0 mm; abdomen, 12.0 mm, width across T2, 9.5 mm; front wing length, 16.5 mm, width, 6.5 mm. Head: Frontal out line (excluding mouthparts) vertically elongate (as in borealis), slightly higher than wide, temporal area strongly arcuate; vertical region mostly flat, finely punctate and polished except concave area laterad of lateral ocelli; ocular two-thirds of ocellocular area irregularly weakly punctate, the ocellar one-third smooth and polished; compound eye more arcuately rounded above than below, about 3 times higher than wide; lateral ocelli moderate in size, the median larger, all located equidistant apart in a weak arc near the supraorbital line; clypeus trapezoidal, distinctly wider basally than high, moderately convex, medially smooth and polished; labrum 1 wider than thick, the triangular rounded tubercles weakly punctate laterally to nearly smooth, the inner angles directed mesolaterally and separated by length of pedicel; malar space almost twice higher than distance between (and including) mandibular articulations, sinuate sub-ocular surface weakly punctate, the convex extremity more or less reticulate; flagellum slightly less than twice as long as scape, FI 2i times longer than distal width, about as long as lengths of quadrate F2-3 combined. Legs: Mesobasitarsus subrectangular, narrowed proximally, less so distally, nearly 3 times longer than widest dimension, its outer surface weakly broadly concave, completely covered with fine dense recumbent pubescence, the distoposterior angle moderately sharply acute, the posterior margin more strongly arcuate on proximal half, the margin nearly straight on distal half; metabasitarsite elongate rectangular, little more than 3 times longer than widest dimension, entirely covered with short strong recumbent pubescence on the outer surface, the posterior margin weakly arcuate basally, straight to spinose distoposterior angled the outer surface nearly flat. Pubescence: Moderately fine throughout, dense and even except longer, looser and more uneven on face, vertex, scutellum posteriorly and on abdominal terga, especially on T5 and laterally on T4 and 3, T6 mostly with short stiff hairs and lacking coverage as on preceding terga; corbicular fringe long and loose, mostly weakly arcuate, the longest hairs about equal to greatest tibial width; metabasitarsal posterior fringe comparatively short, that along the greater median border longer, stouter and only weakly arcuate, the remaining fringe distally progressively shorter, straighter. Color: Head pallid yellow except brownish on gena; thorax above anteriad of tegulae and mesopleuron mostly ochraceous yellow, the moderately wide interalar black band intermixed with yellowish laterally, the scutellum yellow; abdominal Tl-5 orange-yellow, T6 mostly blackish above, basolaterally with longish pubescence, more distally with dense short orange-yellow intermixed with irregularly longer darker hairs. Wings moderately infuscated throughout.

Worker. Length, 18.0 mm; width at wing bases, 6.5 mm; abdomen, 10.5 mm, width across T2, 6.5 mm; front wing length, 15.0 mm, width, 5.7 mm. Morphologically similar to the queen except comparatively smaller throughout. Color: Like that of the queen.

Male. Length, 17.5 mm; abdomen, 10.5 mm, width across T2, 6.2 mm; width at wing bases, 5.5 mm; front wing length, 13.5 mm, width, 5.0 mm. Head: Frontal outline (excluding mouthparts) more or less triangular, broadly arcuate above, little less than twice as high as widest dimension; compound eyes elongate, unevenly oval, slightly less than twice as high as greatest width; vertical region irregularly flat and variously punctate except smooth and polished laterad of ocelli which are located just below supraorbital line, the ocelli about as far apart as f the widest diameter of the median one; mandibular space irregularly convex with weak depressions especially anteriorly, without noticeable pile except posteriorly, the ventrodistal width (including mandibular articulations) nearly equal to the length; labrum flat, without noticeable callosities, the ventral margin bilobed medially; flagellum little more than 3i times longer than scape, FI nearly equal to F3, combined with F2 subequal to F3 plus F4. Legs: Mesobasitarsus subrectangularly elongate, 3 times longer than its widest dimension, the outer surface evenly concave, the distal angles more or less acute and subequal; metabasitarsite rectangular, 3i times longer than wide, exterior surface moderately concave mid-longitudinally, completely covered with short recumbent pile, the acute distoposterior angle and the more rounded distoanterior one equally extended, the posterior margin weakly evenly arcuate, with a short irregular fringe. Pubescence: Longer and more shaggy on most parts than that of either queen or worker. Genitalia, seventh and eighth abdominal sterna (PI. XII). Color: Drab yellow on head intermixed with some black; thorax mostly yellow except paler on anterior thoracic dorsum, the interalar black band not well defined; distal parts of legs (chitinous) brownish ferruginous; pubescence mostly black on coxae and femora, otherwise on legs (tibiae and tarsi) yellow to ferruginous; abdominal Tl-7 mostly ochraceous yellow, the corresponding sterna lighter. Wings lightly infumated, more so over the proximal two-thirds.

Comments. This species is very closely allied to distinguendus (Mor.) and might be only a junior synonym. Further study is warranted to determine the true taxonomic status of both taxa. As far as I have been able to distinguish between this species and distinguendus is a matter of the small differences in the lengths of corresponding proximal flagellar segments, especially in the male.

This species, like its close relative borealis (Kby.), exhibits only slight morphological variations that are within my species concept. However, the color of the pubescence on the head and thorax is especially variable in degree of paleness to the extent that any chromatic decision, let alone that based strictly on morphological differences, must await further study.

Over sympatric areas, captured (presumably) senile specimens of borealis that are encountered are often mistaken for this species, and vice versa; evidently, hybridization occurs in such sympatric distributional areas, ruling out senility as the logical explanation for specific convergence. The numerous questionable specimens seen from such locations are sufficient to indicate hybridization.

Most often in the male, frequently in the worker and less often in the queen, the dorsal thoracic pile anteriad of the interalar band varies from whitish yellow to a deeper shade, approaching the uniform typically golden-yellow of borealis.

Scientific source:

Natural history
Host to B. insularis confirmed by breeding. Likely a host to B. suckleyi and B. fernaldae.

Supported by

Hosts · map
FamilyScientific name @ source (records)
Anacardiaceae  Rhus @ EMEC (1)
Asteraceae  Aster integrifolius @ BBSL (1)

Aster sp @ BBSL (4)

Carduus nutans @ I_ADG (1)

Centaurea maculosa @ BBSL__JPS (1)

Centaurea sp @ BBSL (2)

Chrysothamnus viscidiflorus @ BBSL__JPS (1); BBSL (1)

Cirsium arvense @ BBSL (1)

Cirsium cymosum @ EMEC (1)

Cirsium sp @ BBSL__JPS (13); BBSL (68)

Cirsium @ AMNH_BEE (1); EMEC (10)

Dugaldia hoopesii @ I_ADG (1)

Erigeron speciosus @ DART_ENT (1)

Grindelia squarrosa @ BBSL (4)

Helianthella quinquenervis @ RMBL_ENT (2)

Helianthus annuus @ BBSL (3)

Heliomeris multiflora @ RMBL_ENT (3)

Liatris sp @ BBSL (4)

Pyrrocoma liatriformis @ BBSL (1)

Senecio serra @ RMBL_ENT (1)

Senecio @ RMBL_ENT (1)

Solidago @ EMEC (1)
Boraginaceae  Mertensia oblongifolia @ BBSL (1)

Myosotis laxa @ BBSL (1)

Phacelia @ EMEC (1)
Capparaceae  Cleome serrulata @ BBSL__JPS (3)
Caprifoliaceae  Lonicera @ EMEC (1)

Symphoricarpos albus @ BBSL (1)
Dipsacaceae  Dipsacus fullonum @ BMEC_ENT (2)

Dipsacus sp @ BBSL__JPS (2)
Ericaceae  Vaccinium macrocarpon @ RUAC_ENT (1)
Fabaceae  Astragalus cicer @ BBSL (3)

Astragalus sp @ BBSL (1)

Astragalus @ UCRC_ENT (8)

Hedysarum boreale @ BBSL (5)

Lathyrus leucanthus @ RMBL_ENT (1)

Lupinus argenteus @ BBSL (1)

Lupinus sp @ BBSL (1)

Medicago sativa @ BBSL (2); EMEC (1)

Melilotus alba @ BBSL (1)

Melilotus albus @ EMEC (1)

Melilotus sp @ BBSL (3)

Thermopsis montana @ BBSL (1); UCRC_ENT (1)

Thermopsis @ RMBL_ENT (1)

Trifolium hybridum @ BBSL (1)

Trifolium pratense @ BBSL__JPS (7)

Trifolium repens @ BBSL (1)

Trifolium sp @ BBSL (7)

Vicia americana @ RMBL_ENT (1)

Vicia sp @ BBSL (1)

Vicia villosa @ BBSL (2)

Vicia @ BMEC_ENT (2)
Gentianaceae  Frasera speciosa @ UCRC_ENT (1)

Gentiana parryi @ RMBL_ENT (25)
Geraniaceae  Geranium sp @ BBSL (15)
Herndon, j.d.  1487 @ JRYA__OLYM (2)

1594 @ JRYA__OLYM (1)

1609 @ JRYA__OLYM (1)

1639 @ JRYA__OLYM (1)
Lamiaceae  Agastache sp @ BBSL (4)

Agastache urticifolia @ I_JSA (2); RMBL_ENT (1)

Monarda fistulosa @ BBSL (1); AMNH_BEE (1)

Monarda sp @ BBSL (5)
Liliaceae  Camassia quamash @ BBSL (1)
Malvaceae  Sphaeralcea sp @ BBSL (1)
Onagraceae  Chamerion angustifolium @ RMBL_ENT (1)

Epilobium sp @ BBSL (4)
Ranunculaceae  Aconitum columbianum @ I_JSA (1)

Delphinium barbeyi @ BMEC_ENT (1); RMBL_ENT (5)

Delphinium nuttallianum @ BMEC_ENT (1); RMBL_ENT (2)

Delphinium sp @ BBSL (4)
Rykken, j.  1320 @ JRYA__OLYM (1)

1373 @ JRYA__OLYM (1)

1487 @ JRYA__OLYM (1)

1511 @ JRYA__NOCA (1)

1527 @ JRYA__OLYM (1)

1535 @ JRYA__OLYM (1)

1559 @ JRYA__OLYM (1)

1562 @ JRYA__OLYM (1)

1565 @ JRYA__OLYM (1)

1670 @ JRYA__OLYM (1)

1821 @ JRYA__NOCA (1)
Scrophulariaceae  Linaria dalmatica @ BBSL__JPS (1)

Linaria vulgaris @ BBSL (15)

Orthocarpus tenuifolius @ BBSL (1)

Penstemon caryi @ BBSL (1)

Penstemon confertus @ BBSL (1)

Penstemon harringtonii @ BBSL (1)

Penstemon rydbergii @ BBSL (3)

Penstemon sp @ BBSL (1)

Penstemon washingtonensis @ BBSL (1)

Scrophularia @ AMNH_BEE (1)
_  Withheld @ BBSL (93)

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Updated: 2024-07-15 17:55:36 gmt
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