Photo: gailhampshire / CC BY 2.0

Bombus sylvestris

Forest Cuckoo Bumblebee

A medium-sized cuckoo bumblebee (12–16 mm) with a black body, bright yellow collar and shoulder patches, white tail, and noticeably dark wings. It has no pollen-collecting apparatus and produces no workers. It parasitises the nests of Bombus pratorum and Bombus monticola, invading the host nest, killing or subduing the resident queen, and forcing host workers to rear its offspring. In Switzerland it occurs in woodlands, gardens, and alpine meadows from lowlands to high elevations, flying from April to August. Swiss Red List: Least Concern (LC).