Identification, Images, & Information
For Insects, Spiders & Their Kin
For the United States & Canada
Clickable Guide
Moths Butterflies Flies Caterpillars Flies Dragonflies Flies Mantids Cockroaches Bees and Wasps Walkingsticks Earwigs Ants Termites Hoppers and Kin Hoppers and Kin Beetles True Bugs Fleas Grasshoppers and Kin Ticks Spiders Scorpions Centipedes Millipedes

Upcoming Events

Interested in a 2022 BugGuide gathering in New Mexico?

Photos of insects and people from the Spring 2021 gathering in Louisiana, April 28-May 2

National Moth Week 2020 photos of insects and people.

Photos of insects and people from the 2019 gathering in Louisiana, July 25-27

Discussion, insects and people from the 2018 gathering in Virginia, July 27-29

Photos of insects and people from the 2015 gathering in Wisconsin, July 10-12

Photos of insects and people from the 2014 gathering in Virginia, June 4-7.

Previous events


Subgenus Psithyrus

Bombus unknown - Bombus citrinus Bombus sp. - suckleyi ? - Bombus insularis - female Bombus (Psithyrus) cf insularis - Bombus insularis - female Lemon Cuckoo Bumble Bee - Bombus citrinus - male Mystery bumble bee - Bombus flavidus - female Bombus sp. - Bombus citrinus Bombus 3 - Bombus citrinus Bombus flavidus (= Bombus fernaldae) - Bombus flavidus
Kingdom Animalia (Animals)
Phylum Arthropoda (Arthropods)
Subphylum Hexapoda (Hexapods)
Class Insecta (Insects)
Order Hymenoptera (Ants, Bees, Wasps and Sawflies)
No Taxon (Aculeata - Ants, Bees and Stinging Wasps)
No Taxon (Anthophila (Apoidea) - Bees)
Family Apidae (Cuckoo, Carpenter, Digger, Bumble, and Honey Bees)
Subfamily Apinae (Honey, Bumble, Longhorn, Orchid, and Digger Bees)
Tribe Bombini (Bumble Bees)
Genus Bombus (Bumble Bees)
No Taxon Subgenus Psithyrus
Synonyms and other taxonomic changes
used to be treated as a separate genus (discussion + list and distribution of world spp.)(1)
6 spp. in our area, 30 spp. total(2)
Males are much smaller than females.
Females differ from those of all other Bombus in having the outer surface of the hind tibia convex and densely hairy (flat or concave and largely bare in other, pollen-collecting Bombus). Males have small heads and often have conspicuous bare patches on the apical terga medially.
holarctic, most diverse in Eurasia; in our area, widespread: 4 spp. are transcontinental in the north and range south along the Rockies (except B. ashtoni), B. citrinus ne. US + adjacent Canada, B. variabilis e. half of the US (+QC) to AZ in the south(2)
Social parasites of other bumble bees.
Life Cycle
There is no worker caste, the females invade Bombus nests and lay eggs there to be reared by the hosts(1)
Internet References
Mol.Phylogent. Evol. A phylogenetic analysis of cuckoo bumblebees (Psithyrus, Lepeletier) and bumblebees (Bombus, Latreille) inferred from sequences of the mitochondrial gene cytochrome oxidase I.