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Margaret Murdin, NDB, BBKA president

As I write this at the end of April, the weather is exceptionally cold and my bees will once again be clustered. They should be out foraging on the oilseed rape that surrounds them, but not one is to be seen. This year, with the wet winter and mixed spring weather, some beekeepers have lost colonies, so I must not complain.

June should be a beautiful sunny month and our colonies should be building up nicely in time for the main summer flow. And, with luck, some of us will already have removed the spring harvest.

I am told that in many areas the bees have built up well and may even be making early preparations for swarming. We must remain vigilant, because colonies can – and do – swarm in June. This is particularly likely if the weather is fine, there is a strong nectar flow, insufficient room to store the nectar and little room for the queen to lay. Lack of room is one of the triggers for swarming.

June Gap

In some parts of the country there may still be what beekeepers call a ‘June Gap’. This is the time when the spring flow is over but the summer flowers have not yet opened. It can be a dangerous time for a colony if the spring honey has been removed and there is little forage available. If a colony has built up, and a young queen is laying well, then there will be a lot of brood to feed. If the weather is wet or cold, or there is no forage within reach, then the colony can starve very quickly. If there are no supers on the colony, you can feed a weak sugar syrup in a contact feeder.

If you have partially filled supers on then it is likely that the bees will use these stores. But do check. Remember to remove the supers if you are feeding, otherwise the bees are likely to store excess sugar where there should be honey.

The Varroa Threat

June is also a time when varroa numbers are building up. As the amount of brood increases, so does the number of mites.

A developing larva emits a chemical signal to the house bees to tell them that its cell is ready to be capped. This chemical, or pheromone, must reach a certain concentration before capping will take place. Unfortunately, this same pheromone also acts as a signal to the varroa mites. They can detect the chemicals that make up the pheromone and, at a level just below that needed for capping, they enter the cell. The gravid (egg-laden) female varroa mite then establishes a feeding site for her young by piercing the skin of the larva. Then she hides in the brood food beneath the larva and waits.

This mother mite lays both male and female eggs. After development, the mites mate, the males die, and at least one additional gravid female can leave the cell with her mother. So, we need to take the necessary action to stop their steady but rapid build up.

Integrated Pest Management

BeeBase (www.nationalbeeunit. com) recommends that we monitor the number of mites in our colonies at least four times a year. One of these times is after the spring flow. We can then use Integrated Pest Management (IPM) techniques to control mite numbers. We are not aiming for complete eradication of the mites as it is now accepted that this is not possible.

IPM uses a variety of methods to keep the number of mites below the ‘economic injury level’ which, in the UK, is considered to be 1000 mites per average colony. In reality, of course, this number will vary because all colonies are different. In summer, the mites can live for two to three months and easily complete three or four breeding cycles inside the capped brood cells. The National Bee Unit drone cells are capped for longer, thus giving the mites more time to breed. As part of IPM, we can cull some of this drone brood and thus remove some of the mites.

We need to be careful though, because the drones are not surplus to requirements. They are absolutely essential. Apart from anything else, they are needed for our queens to get properly mated and if we culled all our drones this would have unintended but catastrophic consequences.

Drone Culling

One of the ways to cull surplus drones is to insert a super frame containing drawn comb next to the brood nest.

Normally, the bees will draw drone comb underneath, and attached to, the bottom bar of this frame. When this drone brood is capped and at the red-eyed stage (when it has been capped for about a week) remove it, uncap it, pull out the pupae with an uncapping fork and count the number of mites. Then leave it out for the birds.

If more than 5–10% of the drones are infested, then the mite count is too high and action must be taken or the colony is likely to collapse before the end of the season.

We are, however, fortunate now in that we have approved and effective varroacides that can be used when the supers are on the hive. If your mite count is too high, you must treat. Have a look on the BeeBase website for a list of approved medicines and treat according to the manufacturer’s instructions. If you are unsure about what to do, ask an experienced beekeeper from your branch for help.

Remember, because you are producing food for human consumption, you must, by law, keep a record of all medicines used. Again, details of the information you must keep can be found on BeeBase.

Please don’t be complacent about varroa and don’t assume your mite count is low. Your bees may look healthy, but remember that varroa is still the greatest killer of our honey bees.


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