Temporal patterns of locomotor activity were recorded at four infrared sensor positions along rectangular enclosures in which food was placed at one extreme end and water at the other. The resulting time-series data sets were submitted to a battery of statistical analyses, including periodograms, cumulative periodograms, a variety of activity bout descriptors, and Markov modeling. Comparisons of entrained and free-running circadian rhythms were made between social honey bee workers and nonsocial male and female flesh flies. Three different densities of individuals (1, 4, or 8) of the same species and gender were also monitored within the enclosures. Several fundamental differences between fly and bee activity patterns were revealed. The contribution of the circadian periodicity, as measured by the cumulative periodogram, was enhanced relative to all other frequencies of locomotor activity as the organism density increased for both bees and flies. These results indicate social synchronization of circadian oscillations.