SummaryThe contribution of pre-swarming engorgement by workers to the energetics of long-distance dispersal by swarms of Africanized honeybees was examined, by measuring the volumes and concentrations of nectar from honey sacs of bees from different types of swarms. The extent of worker engorgement varied with the type of swarm; in order of decreasing volumes of honey sac contents, these were: (1) absconding swarms, (2) prime swarms, (3) afterswarms, (4) in-transit swarms, (5) colonizing swarms. Relative to body weight. Africanized honeybees carried greater weights of nectar than have been reported for European honeybees. Calculations based on our measurements of engorgement, and estimates of metabolic rates, indicate that the maximum flight range for reproductive and absconding swarms was 64 km and 131 km, respectively. Colonizing reproductive swarms were moderately engorged, which suggests that these swarms had moved relatively short distances.These observations are insufficient to account for the observed rate of population expansion of Africanized honeybees. The possibility that workers forage from swarms is discussed; such foraging could greatly extend the in-transit period and the distance moved by swarms. Engorgement is discussed as a factor influencing the fitness of swarms.