Getting a colony of bees through winter can be quite a challenge unless you the take the right precautions and prepare properly. Here are my top tips:-
Make sure you have a viable colony with a good laying queen before the end of autumn. You can often spot a failing colony by the bees - not flying in good numbers on sunny days - seeing that they are anxious (walking quickly over their frames) - not bringing in pollen - or if you've seen hive weight drop despite good weather and forage . If weak or failing, combine or make the decision early in autumn to re-queen if possible.
Check for stores - do more than just heft the hive - use spring balances to estimate hive weight - deduct 10% for the possible error in this method - deduct the weight of the hive plus drawn comb and say 2kg for the bees! - My colonies consume between 8 and 12 kgs of stores in the winter (end of October to end of March) depending on their size (with a Bee Cosy fitted) so I plan to have at least 12 kgs of stores - ideally 15 kgs - depending on the strength of the colony.
Feed 2 kg :1 litre sugar syrup if stores are short - warm weather is best- between 12.5 and 15 degrees depending on the level of sunshine during the day - Don't overfeed! - They may still be able to bring in stores from Ivy if they need it and some empty cells for winter brood rearing and clustering is better than a brood full of stores.
Varroa treatment - pick a week when the weather is fair - ideally with some sunshine to raise hive temperatures - the later the better as there will be fewer varroa in the reducing winter brood and more will be impacted by the treatment you choose. Do what you can to keep heat in the hive - varroa treatments work better the warmer the hive.
Hive check and prep - take off queen excluders, replace glass crown boards with wooden ones, reduce draughts in and around the hive, check for gaps between floors / brood boxes / supers / roofs - fix mouse guards. I prefer to leave the plastic trays in my OMFs in and reduce air flow through the hive.
Reduce unnecessary space to help your bees keep a good hive temperature - If you have roofs with big empty spaces fill them with paper / carpet / foam - and critically - if you have small colonies where there may be 3 or 4 frames not occupied take empty frames out and replace with blocks of insulating foam cut to size.
- Check you have your Bee Cosy fitted! - as well as reducing the stores needed in 2 above, it will also help with points 3, 4, 5 and 6.
Good luck for Winter 2015 - let's hope it's kind to our bees!