Figure 1

Seasonal change in the numbers of adult bees (a) and capped brood (b) in three long-term field experiments. The field experiments to obtain the numbers of adult bees capped brood were conducted as carefully as possible because their measurement accuracy could greatly affects the estimation accuracy of apparent longevity. Their numbers accurately counted with the help of an newly-developed image processing software while being directly corrected on enlarged photographs of all combs and the inside of a hive because their numbers obtained from photographs could be counted again at any time when in doubt. An experiment is conducted just after dawn before foraging bees go out anywhere.