Bombus variabilis
Photo: Wikimedia Commons (CC) via https://en.wikipedia.org/wiki/Bombus_variabilis
Overview
Bombus variabilis, the Variable Cuckoo Bumble Bee, is a parasitic species of bumble bee primarily located in North America. Its preferred host species, Bombus pensylvanicus, has dealt with population decline due to habitat loss and climate change. This makes it more difficult for Bombus variabilis to grow in numbers, with less colonies available to raise their young.
The bee possesses a dark face and yellow vertex with dark brown wings. Its thorax has variations between black spots or patches. Females only have black abdomens but males may vary in their hair color patterns.
Bombus variabilis faces severe population declines primarily due to intensive agricultural practices that have eliminated wildflower meadows essential for foraging. Pesticide use, particularly neonicotinoids, directly impacts colony survival and reproductive success. Climate change is altering the timing of flower blooms, creating mismatches with the species' foraging cycles and reducing available nesting sites in higher elevation habitats.
Habitat
This bumblebee species inhabits alpine and subalpine meadows, typically at elevations between 1,500-3,000 meters, where it depends on diverse wildflower communities for nectar and pollen. The species requires undisturbed grasslands with adequate ground cover for underground nest construction and overwintering sites.
