Foraging and the mechanisms that regulate the quantity of food collected ar
e important evolutionary and ecological attributes for all organisms. The d
ecision to collect pollen by honey bee foragers depends on the number of la
rvae (brood), amount of stored pollen in the colony, as well as forager gen
otype and available resources in the environment. Here we describe how broo
d pheromone (whole hexane extracts of larvae) influenced honey bee pollen f
oraging and test the predictions of two foraging-regulation hypotheses: the
indirect or brood-food mechanism and the direct mechanism of pollen-foragi
ng regulation. Hexane extracts of larvae containing brood pheromone stimula
ted pollen foraging. Colonies were provided with extracts of 1000 larvae (b
rood pheromone), 1000 larvae (brood), or no brood or pheromone. Colonies wi
th brood pheromone and brood had similar numbers of pollen foragers, while
those colonies without brood or pheromone had significantly fewer pollen fo
ragers. The number of pollen foragers increased more than 2.5-fold when col
onies were provided with extracts of 2000 larvae as a supplement to the 100
0 larvae they already had. Within 1 h of presenting colonies with brood phe
romone, pollen foragers responded to the stimulus. The results from this st
udy demonstrate some important aspects of pollen foraging in honey bee colo
nies: (1) pollen foragers appear to be directly affected by brood pheromone
, (2) pollen foraging can be stimulated with brood pheromone in colonies pr
ovided with pollen but no larvae, and (3) pollen forager numbers increase w
ith brood pheromone as a supplement to brood without increasing the number
of larvae in the colony. These results support the direct-stimulus hypothes
is for pollen foraging and do not support the indirect-inhibitor, brood-foo
d hypothesis for pollen-foraging regulation.