> We are told that bees use day length as a guide to their activities, eg the queen (no doubt on the advice of her daughters) starting to lay again as the days get longer or reducing the laying rate as they get shorter.  

Very interesting literature about this item is here:

http://onlinelibrary.wiley.com/doi/10.1111/j.1365-2311.2007.00904.x/abstract

Abstract:

Abstract 1. Each autumn in northern regions, honeybee colonies shift from populations of short-lived workers that actively rear brood to broodless populations of long-lived winter bees. To determine if dwindling pollen resources trigger this transition, the natural disappearance of external pollen resources was artificially accelerated or delayed and colonies were monitored for effects on the decline in brood-rearing activity and the development of populations of long-lived winter bees.

2. Delaying the disappearance of pollen resources postponed the decline in brood rearing in colonies. Colonies with an extended supply of pollen reared workers longer into October before brood rearing ended than control colonies or colonies for which pollen supply was cut short artificially in autumn.

3. Colonies with extended pollen supply produced more workers throughout autumn than colonies with less pollen, but the development of the population of long-lived winter bees was delayed until relatively later in autumn. Colonies produced similar numbers of winter bees, regardless of the timing of the disappearance of pollen resources.

4. Mean longevity of autumn-reared workers was inversely related to the amount of brood remaining to be reared in colonies when workers eclosed. Consequently, long-lived workers did not appear in colonies until brood rearing declined, which in turn was controlled by the availability of pollen.

5. Dwindling pollen resources provide a powerful cue that initiates the transition to populations of broodless winter bees because it directly affects the brood-rearing capacity of colonies and indirectly indicates deteriorating environmental conditions associated with the approach of winter.

H E ATH E R R . M AT T I L A 1 a n d G A R D W. O T I S 2 1 Department of Neurobiology and Behavior,
Cornell University, Ithaca, New York, U.S.A. and 2 Department of Environmental Biology, University of Guelph, Guelph, ON, Canada

© 2007 The Authors
496 Journal compilation © 2007 The Royal Entomological Society


Kind regards,

Ghislain De Roeck,
Belgium.

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