Temperature and timing: the art of bee-keeping

Bees can be found in the arctic circle at temperatures of minus 20C, but also at the equator where the temperature is plus 35C.  Russian scientists have found that the trick is agglomeration - bees can't regulate their own temperature but as a mass of 50,000 plus they can collectively withstand a much greater range of temperatures, particularly the cold. 

As "About Insects" describes it
As temperatures fall, the bees form a tight group within their hive to stay warm. Honey bee workers cluster around the queen, insulating her from the outside cold. In summer, the workers fan the air within the hive with their wings, keeping the queen and brood from overheating. You can hear the hum of all those wings beating inside the hive from several feet away.
Nevertheless, as expert bee-keeper David Lee told the SWCBKA, the short mating cycle of the bee depends on a critical temperature in the spring with weather dry enough to allow the queen to mate with enough drones (15 or more) to gain the million sperm needed for three years of laying.  Bad summers have narrowed this mating period with devastating results on colonies.  Imported foreign bees have caused a further weakening of the stock, being even less suited to the damp and cooler conditions in Ireland.  The Irish dark honey bee, Apis mellifera mellifera, is certainly better equipped for surviving "hard" winters, cold springs and wet summers than imported bees.  But even these bees must be left untouched over the winter and early spring, to avoid letting cool air into the hive, or letting in moisture which encourages slugs or snails to enter and spoil the hive.
Man vs. Mite
The other big threat is the veroa mite.  David demonstrated the use of grills and chemical treatments to treat the mites.  These are carefully regulated and best used following advice from a bee-keeping association.  The FIBKA advice is linked here, giving full instructions and sources of the chemicals needed. Without treatment, the mites can multiply year on year, so that a small infestation one year will become a major threat to the bees within a short time.  The mites do not kill the bees, but they eat away at the larvae, often leaving them without wings and unable to fly.

David will continue his series of fascinating talks later in April with a live demonstration at the hives.  News will be posted on this website before the event.