Honey bees collecting pollen from the body surface of foraging bumble bees: a recurring behaviour

We observed this behaviour, previously studied only in North America and as a rare occurrence, on each of the three visits, one per year, we made to the same site, in Italy. Honey bees Apis mellifera L. preferred collecting pollen from red-tailed bumble bees Bombus lapidarius L. than directly from flowers of the woolly thistle Cirsium eriophorum (L.). In another site, which equally had this thistle species as the only plant in bloom, but fewer bumble bees, honey and bumble bees foraged concomitantly on the same flowers avoiding interspecific contacts. In both sites, the honey bees showed easier foraging in the presence of male, than of less tolerant worker, bumble bees. In a third site, the honey bees preferred foraging independently on the smaller flowers of the Tyrol thistle Centaurea nigrescens Willd., while the bumble bees preferred the woolly thistle. Therefore, when plants offer few foraging choices, honey bees may visit less preferred large composite flowers where a crowd of bumble bees hampers their usual foraging mode, but little-reactive males offer pollen collection from their furry bodies, to which honey bees specialize.