Queens fly from March to mid September or the beginning of October; workers from late April to early October, and males from early June (exceptionally late April in the Isles of Scilly) to the end of September. It isalmost certain that in many areas in the British Isles (and particularly in southern England) the species is bivoltine, as freshly-emerged males have been encountered in early June, mid July and late August. The species is known to be double-brooded in Norway and in the Netherlands (Meidell, 1968; Peeters, Raemakers & Smit, 1999). However, precise data to confirm this supposition is nevertheless required for the British Isles.
Parasites: Bombus sylvestris is probably a social parasite in the nests of this species (Richards, 1928; Yarrow in Free & Butler, 1959). In continental Europe, Bombus flavidus is cited as a social parasite of this species (Westrich, 1989). Several Mutilla europaea have been reared from B. jonellus cocoons obtained in Dorset (Haines, 1914).
In Switzerland, Bombus flavidus is recognised as a parasite of this species.