Crotch's Bumble Bee

Bombus crotchii

Classification

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

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Summary

Crotch's bumblebee (Bombus crotchii) is an endangered species of bumblebee characterized by a black head and thorax with yellow markings. It is found primarily in California, where it inhabits warm, dry grassland and scrub areas, feeding on a variety of floral species and playing a critical role in pollination.

Physical Characteristics

Females have a black head and thorax with a yellow dorsal anterior thorax and sometimes yellow on the scutellum. The first metasomal tergum (T1) is black or black in the middle portion. T2 is usually yellow; T3-5 are black or orange, and T6 is black. Males have large eyes and a black interalar band, with yellow hair on their faces and a broad black stripe mid thorax.

Identification Tips

Females are identified by a contrasting yellow band on T2 and an orange-red tail tip, while males are distinguished by large eyes and a black interalar band with extensive yellow on their basal terga.

Habitat

Primarily found in grassland and scrub areas of California, requiring warmer and drier environments. Nests underground, often in abandoned rodent dens. Overwintering behavior is not well known but is presumed to be similar to other bumblebee species, possibly under leaf litter or soft soil.

Distribution

Best known from cismontane California, extant but uncommon in Baja California, Mexico, and into Nevada.

Diet

Dietary generalist feeding on milkweeds, dustymaidens, lupines, medics, phacelias, sages, snapdragons, Clarkia, poppies, and wild buckwheats. Milkweed is a favored nectar source.

Life Cycle

Queens are active from March to May; workers from April to August, peaking in May and June; males from May to September, peaking in July.

Reproduction

Nesting occurs underground, often in abandoned rodent dens.

Conservation Status

Endangered; listed as imperiled as of April 2014 by IUCN, with significant declines observed in range and abundance due to climate change, pesticide impacts, and habitat loss.

Ecosystem Role

As a major pollinator, Crotch's bumblebee supports the growth of various plants, including food sources for other species like monarch butterflies.

Health Concerns

Impact from pesticides, particularly neonicotinoids, which have long-term toxicity effects on bumblebees.

Similar Taxa

Misconceptions

May be confused with Bombus californicus or Bombus occidentalis due to similar color patterns.