This is one of the most difficult and important operations in bee breeding, yet it is the one most often ignored or left to chance.
Timing for drone production... Drones do not become properly sexually mature until they are at least 14 days old and have had five good flying days. See Grafting Time Table.
Feeding for drone rearing... Any colony that is expected to produce good quality drones, must have adequate provisions for doing so, and these provisions also need to be in the right place within a hive and be replaced or replenished on an exact time scale. Liquid feed for drone raising... 1 kg sugar + 1 litre water + Fumidil "B" + Thymol at 4x Manley strength. Consider adding 1 gram of copper gluconate, but only after tests to ensure this does not alter the fertility of the drones. Personally I like to use good clean honey diluted with an equal volume of water.
The original Taber troughs were made of heavy gauge galvanized iron (much thermal inertia) and were 25 mm wide x 13 mm overall depth. The ones that John Atkinson used were stainless steel that was thinner, but they still had a good deal of thermal inertia. They were fitted into shallow frames with three troughs per frame (the shallow frame was much used by Taber & Atkinson, mainly for lightness and portability). I, personally, do not like the broad, but shallow shape as the bees maintaining the brood can have their ability to maintain temperature overwhelmed by the surface area to volume ratio of such a frame. I prefer half width, brood depth frames which improve this aspect, but still may not entirely eliminate it. The troughs that I have used were built into frames, rather than being removable and were made of 2.5 mm thick aero modeling plywood. Future link to frames with pollen & feed troughs. Replace and/or replenish the pollen in these troughs every three and a half days. Six litres of pollen (thawed from frozen, not dried) are required to produce a batch of 300 drones. (Atkinson)
Extending the drone raising season... This includes mechanisms to improve or cause drone retention after they would normally be expelled from colonies.
April - September are the normal limits for extending the drone rearing season using pollen in trays (Taber, Laidlaw, Atkinson).
Keep drones raised in July in a queenless colony... Sustained by extra frames of sealed brood every 3 or 4 days. Alternatively keep the drones in mating nucs with a succession of virgin queens (needs intensive daily inspection and a constant daily flow of fresh virgins).
Health and viability of drones... Varroa treatment using Formic Acid renders the drones dry and impotent. Thymol effects drone survival and viability in the same way as formic acid, but I do not know the detailed figures. Varroa infestation and Apistan treatment both affect drones. Colonies intended to provide drones for insemination should be treated the previous year so that the reared drones are not affected by fluvalinate or any other residues.
Drone rearing cassette frames Drone excluder is available and can be used to enclose cassette frames in a queenright colony for drone production (This is where John Atkinson's shallow frame can best be used to good effect). Use full sheets of drone based foundation 640 cells per Sq Decimetre (5.9 mm) or larger, 22 mm side bars and 13 mm excluder frames held on by dowels and small hasps. Enclosure ensures that no rogue or extraneous drones become mixed with the batch and ensures that they are close in age.
The brood is only "young" for three an a half days.
An old queen that has become a drone layer, (providing she is of suitable parentage), can be utilised for producing drones providing that fresh sealed brood is added every 3 (or 4) days to make up for those that are not being laid by the queen.
Drone eggs or sealed drone brood can be transplanted from colonies containing the "Right" queen to any other colonies for raising and release. The transplants of eggs can even be posted to other beekeepers... Proven by Albert Knight.
(See Egg Transplanting).
Drone comb is often removed by beekeepers in the mistaken belief that they will get more honey as a result. To obtain early drones we must ensure that there are patches of drone sized cells available to the bees as the colony expands in spring. To this end I have in the past often fitted triangles of drone foundation in the upper corners of brood frames or as vertical strips down each side of a frame ensuring that the number of drone cells in the particular frame is between 20% or 30% of the frame area. I have also inserted extra patches of drone cells, using a 'cookie cutter', into frames that already contain patches of drone cells.
The exact percentage of drones that bees will raise for themselves in feral colonies varies between 12% and 23%... more here later)
At some times during the year the bees prefer to draw drone cells... See Population Dynamics. I wonder if providing a frame of drawn drone comb would alter this urge to build drone comb. It may be a shortage of drones rather than a shortage of drone sized cells which stimulates the drawing of drone rather than worker cells.
Drone Cell Size... Complementary to the work being carried out on worker cellsize I believe that there is a fundamental relationship rather like the 3 queen, 4 drone, 5 worker cells to the 15/16" measure that is quoted in books more than a century old. This would indicate a drone cellsize of 6.125 mm as being the ideal size, however since deciding to make a mould for this size, I have found out about the existence of a 5.9 mm cellsize leaf press, owned by a friend of mine. He reports that when this size of foundation was originally given to bees it was used to draw drone cells and so I will use this to complement my 4.9 mm worker foundation.