Despite the host of this species (Bombus hortorum) being relatively widespread and common, Bombus barbutellus is a rather scarce species which is difficult to encounter. It is a rather large species with a yellow collar and faint yellow hairs around the scutellum and white-haired tail, sometimes fringed with yellowish hairs. Males can be similar but also have yellow hairs around the first tergite on the abdomen. They tend to have more golden-yellow colouration and sparser hairs than B. hortorum. It has undergone a relatively stark decline and is classed as Endangered in Ireland.
Distribution in Ireland: Widespread across much of Ireland but rather scarce and never common.
Flight Period: Females appear in mid-May, with males and new females emerging in July and flying until mid-September.
Habitat: Found in a wide range of habitats where the host has strong populations.
Flowers visited: Visits a wide range of flowers but particularly attracted to nectar-rich composites such as Creeping Thstile, Spear thistle, Knwpeed as well as various Fabaceae and Lamiaceae such as Hedge Woundwort, White Clover and Red Dead-nettle.
Personal Records: I have recorded this species on two occasions, both around the Sheskinmore area of west Donegal. Here I have found females nectaring on White Clover and Purple Loostrife around unimproved grassland. There are strong populations of Bombus hortorum in the area.