IN species with haplodiploid genetic systems, full sisters are more closely related to each other (r = 3/4), and less closely related to their brothers (r = 1/4), than to their daughters and sons (r = 1/2). The classical theory for the origin of hymenopteran eusociality predicts that in many primitively or facultatively eusocial species, workers should exploit this relatedness asymmetry by laying male-destined eggs while allowing the queen to lay gyne-destined (reproductive female) eggs(1-3). This prediction is satisfied in many species where colonies are founded by solitary gynes(4-8). Here we describe a surprising reversal of the classical pattern. In colonies of the bee Halictus ligatus (Halictidae), queens produced most of the male-destined eggs whereas workers produced many of the gyne-destined eggs. We suggest that this pattern may result from temporal constraints on the production of reproductive brood, and that it may be common among primitively eusocial species.