Multi-Purpose Nucleus Formation
One of the most effective biological anti-Varroa procedures being widely used in Continental Europe at present is the formation of nuclei using combination brood combs; the top half of the comb, in a standard brood comb is worker comb, while the lower half of the comb is drone comb. It is relatively simple to produce such combs; in the late spring early summer. Merely insert a worker brood comb, with the lower half of the comb cut away leaving an empty space equal to half of the comb area of a standard brood comb, into a strong colony (bees covering at least eight frames!). A frame so treated should be placed between the last brood frame containing brood and the 'pollen' comb at each side of the brood nest. The 'pollen' comb is easily identified; it is the comb on the fringes of the brood nest. If the bees are prospering the lower half of both frames will be filled with drone comb within a couple of days. Around 17 days later (20 days at the latest!) check these combs - if the bees have done their homework both combs should be fully laid up and well sealed. These combs should now be removed to a nucleus hive with the adhering bees BUT WITHOUT the queen. The procedure should be done with all hives in an apiary at the same time, so that a number of 4 or 5 frame nucs can be made up - depending on the size of the apiary! The removed combs should be replaced by more combs with the lower half cut away, as the second last frame on each side of the hive.
These nucs should be removed to another apiary at least a mile from the parent apiary. Check the nucs at two day intervals. When all the drone brood has emerged treat the nuclei with a 3% sugar/oxalic acid solution dosing each occupied frame space with 3 - 4 ml of solution. The following day give the nucs either a young caged queen or a ripe queen cell or a frame of eggs and open brood. Ensure the bees have adequate stores at all times.
A 'belt and braces' method of making sure that the queen is not taken when the combi-frames are removed, is:
The combi frame method of drone removal is only effective up to around the end of June. If done properly the removal of around 6 combi combs up to that time will have the effect of removing a massive amount of Varroa mites from the parent colony in the sealed worker and drone cells. Research has shown that around 85% of the mites in a bee colony are in the brood cells at any given time. It is now common knowledge that the Varroa mite has a preference for drone brood.
The use of this method gives the beekeeper:
All the colonies can be treated in the late autumn/early winter with whatever method suits the particular beekeeper.