The Gypsy's Cuckoo Bumblebee (Bombus bohemicus) is a species of socially parasitic cuckoo bumblebee found in most of Europe with the exception of the southern Iberian Peninsula and Iceland.
It is a generalist parasite, successfully invading several species from the genus Bombus. 
The defining physical feature in comparison to non-Cuckoo bumblebees is that Bombus bohemicus lacks corbiculae, or pollen sacks, on its posterior tibia, instead the area is covered in dense hair.
The first transverse band (close to the head) of Bombus bohemicus extends 1.5-2 mm below the base of the wing and is only sparsely hairy.
This first band (or collar) is usually yellow-orange but can also be white (like on the photos).
Its wings are strikingly dark.

Pfänder Mountain, Bregenz, Vorarlberg, Austria, 1 August 2020