Queens appear early in the year, exceptionally in February (G.M. Spooner, pers. comm., had one visiting Salix blossom (Salicaceae) on 18th of the month), though the usual time is March and April onwards. Young queens are frequently noted in the late summer, and have been observed in mid September and as late as mid November (I had one flying in a Devon garden in December). Workers are active from mid May (rarely) or mid June to the middle of October, and males from the beginning of July to late October.
Parasites Bombus vestalis is a common social parasite of this species (cited as Psithyrus vestalis; Sladen, 1912; Alford, 1975; Løken, 1984; Westrich, 1989).
Taxonomic status: B. terrestris, B. maderensis and B. canariensis have been regarded both as conspecific and as separate species.
Erlandsson (1979) argued that the dark individuals from the Canary Islands, previously placed within B. terrestris by for example Krüger (1954, 1956), are a separate species, B. canariensis. Erlandsson also argued that individuals from the island of Madeira, previously placed within B. terrestris by Bischoff (1937), are a separate species, B. maderensis. In both cases the morphological characters used to support these distinctions are not strongly divergent from the broad variation within B. terrestris in the broad sense. Rasmont (1984) regards these three taxa as separate species, but Pekkarinen & Kaarnama (1994) treat them as conspecific.
Recent work by Estoup et al. (1996) has found that although mainland populations do not vary significantly among themselves in mitochondrial genes, all island populations studied (from six Mediterranean islands in addition to B. canariensis) show significant differences from the mainland populations.
Consequently, viewing these three nominal taxa as separate species may be one interpretation, but this appears to depend on adopting a species concept that admits little colour, morphological or genetic variation within a species and regards current geographical isolation as highly indicative. I prefer to regard these taxa as conspecific until further evidence is available.
Nomenclature: The orthography of Linnaeus (1758) employs a long 's' (similar to 'f' or 'f'), a common practice of the period. This convention has since changed and recent authors have consistently used 's'.
Day (1979) described how none of the admissable syntypes of A. terrestris Linnaeus is in agreement with the current usage of the name.
To reaffirm the traditional usage of this particularly widely used name, a case was made to ICZN by Løken et al. (1994). This sought an Opinion from ICZN (ICZN, 1996) that set aside, by use of its Plenary Power (ICZN, 1985: Articles 78b, 79), the lectotype designation for A. terrestris by Day from application of the Code (ICZN, 1985), and then designated a neotype (ICZN, 1996: 64) to conserve the traditional usage of the name for even the narrowest concept of the taxon (ICZN, 1985: Article 75).