This is one of the first bumblebees to become active in the spring, with queens having been observed on the wing on several dates in February, the earliest on the 3rd of the month. In Dorset, G.M. Spooner (pers. comm.) noted a queen at male Salix catkins on February 18th. The latest date in the year for active examples of this caste is September 30th. Workers fly from late April to the end of October, and males from mid May to mid September. Although some of the later dates may concern the progeny of queens which emerged from winter diapause late in the spring, it is also very probable that in favourable seasons and localities,the species successfully completes two nesting cycles in the same year. The species is similarly considered to be bivoltine in Norway (Meidell, 1968).
Parasites: Bombus sylvestris is the regular social parasite in nests of this species (Sladen, 1912; R.C.L. Perkins, 1923; Richards, 1928; Alford, 1975). Other Bombus species which may usurp B. pratorum nests are B. campestris (Pouvreau, 1973), B.rupestris (van Honk et. al, 1981) and possibly B. barbutellus (V.R. Perkins, 1892), although it is likely the latter record was an error.
Introductions: This species was deliberately introduced into Sydney, Australia, but is not known to have persisted (Oliff, 1895). Until the twentieth century B. pratorum was not known in Ireland, where it is now well established (see references in Alford, 1975, 1980)