Collective decision-making in honeybees: A multi-agent simulation study. Honeybees show the impressing ability to choose the optimal nectar source out of several distributed sources in the environment. This decisions are made without any central unit of decision and without individual assessment of all nectar sources by all foragers. The decision making is the ultimate result of a process that involves competition among cohorts of foragers that advertise their foraging target via waggle dances. Finally, the cohort foraging on the optimal target succeed automatically and the main fraction of foragers of the colony converges to the optimal food source. We developed a multi-agent simulation of a foraging honeybee colony in which each single foraging bee is represented by an agent, that is an autonomous instance of a computer program. Using this simulation, we investigated the properties of the honeybee foraging system and we evaluated its efficiency in fluctuating environments. K e y w o r d s : honey bee, foraging decisions, multi-agent simulation, mathematical modeling,