Search Field Guide
Advanced Search
MT Gov Logo
Montana Field Guide

Montana Field Guides

  • Home - Other Field Guides
    • Kingdom - Animals - Animalia
      • Phylum - Spiders, Insects, and Crustaceans - Arthropoda
        • Class - Insects - Insecta
          • Order - Sawflies / Wasps / Bees / Ants - Hymenoptera
            • Family - Bumble, Honey, Carpenter, Stingless, & Orchid Bees - Apidae
              • Species - Fernald's Cuckoo Bumble Bee - Bombus flavidus
Fernald's Cuckoo Bumble Bee - Bombus flavidus
Other Names:  Bombus fernaldae

Native Species

Global Rank: G5?
State Rank: SNR

Agency Status


External Links

General Description
For definitions and diagrams of bumble bee morphology please see the Montana State Entomology Collection's Bumble Bee Morphology page. A small species: queens 17-18 mm, no workers. Hair medium length; hind leg tibia with convex outer surface and covered with hair (no pollen basket); Hair of face black with at most a few yellow hairs above antenna base; T1 often black in west and yellow in east; T2 black; T4 mostly yellow with a small patch of black at front; T5-6 black; T6 strongly curled under abdomen and pointing anteriorly. Male 11-15 mm; eye similar in size and shape to that of any bumble bee female; antennae medium length, flagellu 3X longer that scape; hair of face black; T1-3 sometimes nearly completely yellow; T4 yellow with at most a few black hairs near midline; T6-7 orange that often have paler tips (Kock et al. 2012, Williams et al. 2014).

Range-wide, queens active March to September, males May to September (Colla et al. 2011, Koch et al. 2012, Williams et al. 2014). In southern Ontario, queens active May to September, males June to September; earliest spring record 27 May (Colla and Dumesh 2010). In California, queens reported early April to early August, males early May to late September (Thorp et al. 1983).

Diagnostic Characteristics
Please see the Montana State Entomology Collection's Key to Female Bumble Bees in Montana. Outer surface of the hind tibia convex, densely hairy and lacking a pollen basket separates B. fernaldae from other Bombus except other cuckoo bumble bees. A combination of an occiput with predominantly yellow hairs, hairs of face predominantly black around the base of the antennae, and T6 often tightly curled forward under the abdomen, separate females of this species from other Bombus (Colla et al. 2011, Koch et al. 2012).

Species Range
Resident Year Round

Recorded Montana Distribution

Click the map for additional distribution information.
Distributional Information Provided in Collaboration with the
Montana Entomology Collection at Montana State University


Range Comments
Widely scattered in montane and boreal regions, from the Appalachian Mountains of the eastern US and adjacent southern Canada across the aspen parklands of central Canada to the Rocky Mountains, Cascades, and Sierra Nevada, from Alaska to southern California and northern New Mexico (Williams et al. 2014); to at least 3655 m elevation in California (Thorp et al. 1983).

Poorly described. Openings and meadow edges in montane and boreal forest, including to near treeline or above (Ostevik et al. 2010, Wilson et al. 2010).
Predicted Suitable Habitat Model

This species has a Predicted Suitable Habitat Model available.

To learn how these Models were created see

Food Habits
Visits a variety of of plants, including Arctostaphylos, Asclepias, Aster, Chrysothamnus, Cirsium, Eriogonum, Haplopappus, Helianthus, Hieracium, Melilotus, Potentilla, Rhododendron, Ribes, Rubus, Senecio, Smelowskia, Solidago, Tanacetum, Taraxacum, Trifolium, Vaccinium, Veratrum and Viguiera (Thorp et al. 1983, Wilson et al. 2010, Colla and Dumesh 2010, Colla et al. 2011, Koch et al. 2012, Williams et al. 2014).

Reproductive Characteristics
Parasitic on other Bombus. Queens invade nests of host species, subduing or killing the host queen and nesting in colonies of other bumble bees, especially B. rufocinctus, but recorded from colonies of B. appositus and B. occidentalis (Hobbs 1965b, 1966b, 1968; Williams 2014). Also reported to parasitize particularly nests of bumble bees in the subgenus Pyrobombus, but host specificity not clear (Hobbs 1967). Host workers raise the parasite brood, so B. fernaldae produces no workers, only queens and males.

Login Logout
Citation for data on this website:
Fernald's Cuckoo Bumble Bee — Bombus flavidus.  Montana Field Guide.  .  Retrieved on , from