Fig. S1. Subspecies differences in onset age of foraging. Hive entrances were observed for approximately 5 hours each day during peak foraging activity on days indicated in plot. Marked focal bees returning to the hive with pollen or nectar loads (see Methods) were counted and killed in liquid nitrogen. A subset of foragers collected at 16- or 17-days of age was analyzed (for brain gene expression) as the F group in Experiment 1. For colony 1 (A. m. mellifera host colony), a final census was taken at day 28; the plot is the proportion of bees from the total census (killed bees plus remaining bees at final census). For colony 2 (A. m. ligustica host colony), the plot is the proportion of bees introduced to colony. Because no subspecies-specific differences in survival were observed in colony 1 or in a previous study (13), the use of introduction numbers should provide unbiased results. Note that the first foragers observed for the two subspecies were roughly the same age (8- and 9-days of age for ligustica and mellifera, respectively).