Yellow-faced Bumble Bee

Bombus vosnesenskii

Classification

Phylum: Arthropoda
Subphylum: Hexapoda
Class: Insecta
Order: Hymenoptera
Family: Apidae
Subfamily: Apinae
Tribe: Bombini
Genus: Bombus
Species: vosnesenskii

Pronunciation

How to pronounce Bombus vosnesenskii: /ˈbɒmbəs vɒsnɪˈzɛnski/

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Images

Bombus (Pyrobombus) vosnesenskii by the Smithsonian. Used under a CC0 license.

Summary

Bombus vosnesenskii, or the yellow-faced bumblebee, is a highly abundant and significant pollinator native to the west coast of North America. It plays an essential role in agriculture, particularly for greenhouse tomatoes, while exhibiting adaptability in various habitats.

Physical Characteristics

Short, even hair; rounded angle of the basitarsus; square face; fringed hair on hind legs forms corbicula (pollen basket). Queens size: 18-21 mm; Workers size: 8-17 mm; Males size: 10-15 mm; Black and yellow hair pattern.

Identification Tips

Queens and female workers are almost always identical in coloring, featuring almost entirely black thoraxes with yellow stripes at the head and T4 segment. Males may have more yellow on their sides extending up the back of the thorax.

Habitat

Chaparral, oak-woodland savannah, foothills, coastal areas, and urban regions.

Distribution

From British Columbia to Baja California, the most common bumble bee species in the Pacific States, especially in cismontane California and lower elevations.

Diet

Generalist diet visiting a wide range of plants, including Lupinus, Cirsium, Eriogonum, Phacelia, Clarkia, and Ericameria.

Life Cycle

Queens establish underground colonies in spring, laying eggs that hatch into workers. The colony grows over summer; reproductive bees are raised towards the end of the season.

Reproduction

Queens leave the nest to mate with males; after mating, they hibernate and start new colonies the following spring.

Ecosystem Role

Important pollinator, especially significant in commercial agriculture for greenhouse tomatoes.

Economic Impact

Critical pollinator for greenhouse tomatoes, resulting in higher quality fruit compared to human pollination methods.

Health Concerns

Affected by parasites including Kuzinia (phoretic mite) and Crithidia bombi (protozoan); generally not causing severe declines individually but potentially harmful in combination with other stressors.

Evolution

The genus Bombus is monophyletic and contains approximately 250 species, phylogenetically close to sting-less bees and honey bees, with B. vosnesenskii in the subgenus Pyrobombus (short-faced clade).