> Colonies kept in total darkness and constant temperature in Canadian sheds still resume broodrearing.

My day job is breeding mice to study genes involved in reproduction and DNA repair. The mice are housed in a highly controlled environment with all air and water sanitized and piped in. The food is irradiated. There are no windows, the lights are on timers. Nevertheless, there is an obvious decrease in breeding in the fall and a surge in the spring. Occasionally, we chat about *how they know it's spring* but nothing ever comes of it. 

It may be that many (not all) plants and animals are on a hardwired annual cycle. It seems fairly clear that changing conditions can override this, but in the absence of environmental cues it kicks in. You can see how both mice and bees may spend a very long time in total darkness with only minimal external influence, so an internal calendar would be highly beneficial.

Pete

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