Seasonal demographics of a colony headed by a vigorous young queen, shed wintered in Manitoba. Each band of color represents the proportion of bees in each 12-day age class at any time point. Red (0-12 days of age) through green (61-72 days) age cohorts represent short-lived “summer bees,” which rarely live longer than two months. The blue and violet age classes are the long-lived “winter” (diutinus) bees that hold down the fort when there is no incoming pollen (and thus little recruitment). The dotted line represents the number of cells of brood. The numbers along the x axis represent the average age of all bees in the hive at any time point.