CHESHIRE BEEKEEPERS' ASSOCIATION

Apes curamus et nos curant (We look after bees and they look after us)
Founded 1899
Registered Charity No. 227494
We've been buzzing over 100 years 1899-2016

Article - Will your bees survive this winter?

Albert Einstein was once asked by one of his students why the questions on this year�s exam paper were the same as last years. �Yes they are�, Einstein confirmed, �but this year, the answers are different!�. The same could be considered to apply to beekeeping and preparing colonies for the coming winter. The traditional methods of preparing colonies for winter, as documented in many of the classic bee books, will no longer ensure your colonies survive.

As you read this in early September, do you know how many varroa mites there are in each of your colonies? If the total in any colony is more than 1000, then that colony is at risk.

Have you carried out any techniques to reduce the number of mites in your colonies during the summer? Thirty mites in a colony in March can increase to over 1000 by September if no action is taken to control their numbers.

Estimating the number of mites can be done by either uncapping a sample of drone pupae or by counting the mites which drop through an open mesh floor. At this time of year colonies have little if any drone brood so this leaves natural mite drop as the only option to make an estimate. Insert a monitoring tray under the mesh floor for 3-4 days, then remove it and count the number of mites on the tray. Divide the number of mites by the number of days the tray was in place. If the average daily mite drop (in September) is more than 4/day then you should do something to reduce the mite levels. If the number is more than 8/day you must act now or risk losing your colony.

Did you see any other warning signs when you last inspected your colonies? Were there bees with deformed wings, mites visible on the bees or on the comb, or evidence of uncapped pupae which had died in the cells? These are signs of heavy varroa infestation. If you saw any of these signs and you don�t do something urgently, then your colony is likely to collapse, and it is certainly unlikely to survive through the winter.

At this time of year, colonies have a reducing quantity of brood and an increasing number of mites. These mites have to enter brood cells to reproduce, so there are more mites entering each brood cell. The resulting increase in infestation of each larva has a big impact on the health of the developing bee, and these bees are destined to be the winter bees in the colony.

If there are too many mites in your colony at this time of year, what can you do about it? Many of the biotechnical methods, which can be used during the active season to reduce the number of mites, are not suitable for use this late in the season. These methods include trapping mites in drone cells, dusting colonies with fine powders and the artificial swarm. Drone trapping isn�t possible if there is no drone brood in the colony, and it is too late to disrupt colonies with an artificial swarm. Dusting takes many weeks of repeated treatments to reduce an excessive number of mites to a low enough level. If you haven�t been doing this throughout the summer, you don�t now have enough time left to use this method to reduce mite numbers sufficiently. The traditional varroacides, Apistan and Bayvarol are no longer reliable as most colonies are now infected with mites which are resistant to these treatments. This leaves a very limited number of available options.

The only treatment registered for use in the UK which will kill resistant mites is Apiguard. It is 90-95% effective but its effectiveness is temperature dependant. The recommendation is that the ambient temperature should be at least 150C. We may be lucky and have a warm September; we certainly haven�t had a warm summer!

It is recommended that you only use Oxalic acid when there is no brood in the colony to avoid the risk of damage to brood. However, if the number of mites in your colony is excessive, you cannot wait until December/January to treat as this will be too late, the damage will already have been done, and the colony will almost certainly collapse. Given the choice of treating immediately, or leaving the colony infested with mites until December I would not hesitate to treat now.

There are treatments registered for use elsewhere in the world which are not registered for use in the UK. I understand some of these can be obtained from suppliers overseas.

Whatever you use, you should keep records of the treatments applied to each colony and take all reasonable precautions to minimise the risk of contamination to any honey. If contamination is found, you could be open to prosecution.

In addition to treating colonies to minimise the number of varroa mites, feeding each colony should encourage the queen to keep laying for longer, thus increasing the number of healthy winter bees raised in your now mite �free� colony. This will give the colony the best chance of surviving through the winter. Finally do ensure that colonies have adequate stores to last until spring.

Beekeeping has become more difficult in recent years, but with a little extra care and effort we can help our colonies survive the winter. You can be sure that if we do, they will more than repay us next year. If we don�t help them (and no one else will), they will not survive! Good luck.

Graham Royle

If you want more information on varroa the NBU produce an excellent booklet �Managing Varroa� (make sure you have the latest 2005 edition). If you don�t have a copy ask your bee inspector, or if you have internet access download a copy from the Bee Unit web site http://beebase.csl.gov.uk.

© 2015 Cheshire Beekeepers' Association