Univoltine over much of its range but partially bivoltine in places. Queens fly from late February or early March to late September, workers from early June (exceptionally early May) to the beginning of October, and males from mid June to late October.
Parasites: Bombus bohemicus is a well-known social parasite of this species (Sladen, 1912; Cumber, 1949; R.C.L. Perkins, 1923; Reinig, 1973, 1976; Alford, 1975; Peeters, Raemakers & Smit, 1999).
The flight period on the Faroe Islands is from early April until mid-October (Jensen & Madsen, 2018)