Brood care by male bumble bees.

Male Bombus griseocollis (Hymenoptera: Apidae) share in the brood care of nestmates by incubating pupae (usually during the first few days after they emerge as adults). Male posture during incubation of a pupa is identical to that observed for females. Pupae incubated by males were 4 degrees C-6 degrees C above the temperature of unincubated pupae. Although this increase was not as great as that caused by workers or queens, it was an important factor in warming pupae. Incubating males may benefit nestmates incidentally without lowering their own individual fitness.