A polylectic species with a strong pereference. Praz et al. (2019) report pollen foraging to eight plant families but had a pronounced affinity for the pollen of Crocus (Iridaceae), which contributed 62.4% to the total pollen grain volume and was recorded in 20 out of 24 scopal loads.
Praz et al. (2019) also report that this finding is supported by field observations at five different localities in the Swiss and French Alps, where several females of A. allosa simultaneously harvested pollen on Crocus. They also noted that many females were observed to collect the pollen from Crocus flowers late in the season, at a time when flowering Crocus were restricted to small patches where snow had remained particularly long.
Other pollen sources are Asteraceae (Cichorioidea, Asteroidea and Carduoidea); Ranunculuaceae; Brassicaceae; Potentilla type, Geum sp. (Rosaceae); Helianthemum (Cistaceae); Gagea (Liliaceae), Fabaceae.