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Drone Management

Bee Culture – March, 2006

by Walt Wright

Drones have historically been the subjects of bad press. Beekeepers recognize that drones are a drain in colony resources and some try to limit drone comb to reduce populations of drones. A study was conducted in recent years of the production impact of drone populations. As expected, the colonies with higher drone populations produced less surplus honey. While the results were a foregone conclusion, the degree may have surprised some. Drones have hearty appetites. Their job is strenuous.

The bee colony sees drones as a necessity. They will rear drones very early in the season to support mating of build up supersedure queens and have a large number of drones to maintain in the air for the swarm replacement queens. In anticipation of the reproductive (swarming) season, the colony will make provision for drone cells on a priority basis. To maintain good colony morale, they need to have about 20% of the brood comb surface in drone cells for most of the active season. Because of the larger size of drone cells the population head count increase does not equal 20% with less cells per square inch and the longer drone development time. That 20% may seem high, but it is based on observation of feral bees permitted to do it their way. If that number falls to 10%, the colony will often improvise additional drone cells. When they improvise, it might not be to the beekeeper’s liking. Lumps of drone cells complicate inspection, and patches of comb converted from worker to drone cell size are permanent. The beekeeper is justified in not desiring drone brood cells in the basic over wintering brood nest. Patches of drone brood comb within the winter cluster are not in his, or the colony’s best interest.

In the wild brood nest, the drone brood comb is located on the outside of the total comb. It is sometimes separated from the worker brood comb by a comb of feed pollen. Irregular chambers at the sides, such as a hollow in the connection of a branching limb are often completely filled with drone cells. This arrangement serves them well. In mid-winter, when brood rearing starts, the focus is on rearing working brood. Workers are needed to replace cluster population declining from fall worker bee die-off. Drones are not needed yet. Solid worker comb in the brood nest warmed area is the most efficient means to increase worker population. Rearing drones in mid-winter is an unnecessary drain on resources that should be applied to the early season objectives. Drone cells in the basic winter brood nest will be populated and create resource waste. Wintering is troublesome enough without wasting resources.

In my area, winter brood is “batched.” Eggs are laid in a short period for the first and second brood cycles. As evidence of this batching, you can open a colony in February and all brood is capped, no open brood. If the queen were laying on a daily basis, there should be nearly as much (8/21) open brood and eggs as capped brood. We see this early brood batching as a safety margin in the honeybee survival format. During the first brood cycle in mid-winter, the colony is still losing fall bees and the cluster is shrinking. The cluster continues to shrink until emergence of the second brood cycle. The first batch didn’t stem the tide of fall bee loss because it was smaller, but the cluster often shows an increase in size with the second cycle emergence. The build-up is on. Be patient with this discussion – this line of thought is headed toward application of these concepts.

The experts cannot think in terms of brood cycles. They are locked into the population growth curves generated by C.L. Farrar more than 50 years ago. Those exponential growth curves were developed from package bee growth. The starter colony, operating in the establishment mode, builds comb as fast as possible and populates that comb as they go. Data in that mode is not relevant to the process of the over wintered colony. In my area, the over wintered population growth shows a temporary increase with emergence of early brood cycles and a decline due to continued fall bee losses between emergence periods. At the end of the second brood cycle, the decline is often more of a leveling off than a real decline. But the total population can show increase, no gain, or decline in different colonies. This makes a rather lumpy curve for population growth of the over wintered colony at the lower, early season starting end.

Toward the end of the second brood cycle, in late February here, the colony is ready to start rearing drones on a priority basis. They may have reared a few in random cells along the way, but drone rearing takes on urgency at this point. It takes over a month to get mature drones on the wing in sufficient numbers to support the impending mating season. And the swarm issue season starts in about five weeks. Note that in the interest of efficiency, they delayed mass drone rearing as long as possible. Now, its mandatory to support species survival requirements.

If the colony does not have a comfortable number of drone cells in handy reach of the cluster, they are forced to improvise more drone cells to populate. Several options are available to them. Some of the popular options follow: If there is excessive bee space between the brood chamber top bars and the bottom bars of the next higher box, they can put a whole row of drone cells crosswise in between on each frame of the brood nest. If there is extra space within the cluster, they will sometimes build clumps of drone cells that jut out into those spaces between frames or into the bottom board access space. It’s sometimes amazing how much wax the colony has stored that can be used for those special structures. Of those two options, the rows of cordwood drone cells in the interbar space gave me the most grief. The problem separating the two boxes was bad enough, but what concerned me more was the terrible waste of colony energy. The colony had invested resources in those drone pupa that were wiped out in a minute by the bungling beekeeper. Over time it was learned that the condition could be avoided by insuring proper bee space between the frames of the boxes. Haven’t seen it in years.

It seems that the colony would rather build drone cells with available old wax than convert worker brood cells to drone cell size. This preference may just be forced on them because they are rearing all the worker brood they can safely protect. If the worker brood cells are populated with an arch at the top of the frame, upper outside corners of the frame can be reworked from worker cells to drone size cells. Barring that option, as a last resort, they will convert cell size anywhere within the basic brood nest.

One other work-around that is sometimes used provides some evidence of just how acute the need actually is. If they find drone cells in the overhead capped honey, they will use them. Even outside the cluster, they will move or consume the honey and prepare those cells for eggs. They do this with a remote mini-cluster, and escort the queen up there to lay. A contingent of bees maintains the mini-cluster to care for and warm the drone brood.

Changing the subject abruptly, the literature tells us that the colony doesn’t like to store pollen in drone size cells. There is little, if any, definition of how to apply that tidbit of information to your hive management. Also missing is the information that the colony doesn’t mind storing honey in drone cells. I see the colony’s reluctance to store pollen in drone cells as another case of advance planning in the survival traits of the honeybee. Pollen is difficult to move, and generally must be consumed as feed. When the colony reaches that point in the build up where drone rearing becomes urgent, drone cells with stored pollen would be detrimental. Honey in drone cells can be consumed or moved, the old “ounce of prevention” thing. Applying this colony preference to hive management is part of following recommendations.

Application of all of the above is quite simple. First, you need to accept an amount of drone population that creates a sense of well being in the colony (morale). Then, you need to provide enough drone comb to accomplish that. To make it easy on yourself, provide the drone comb where the colony work-arounds impact your work load or convenience the least. The following recommendations do that.

Help the colony do it their way. Place drone comb in the outside slots of the brood chamber(s). Drone comb in the outside slots has multiple advantages for the colony. The delayed need for drones in the build up has already been mentioned above. The reverse is true in the fall. Worker brood rearing is normally extended beyond drone rearing. This permits the colony to fill that outside frame with honey sooner. They want that outside frame filled with honey, regardless of cell size. Generally, the second frame in is used for feed pollen. The smaller cluster has both winter brood rearing feed requirements in just a few frames, and they often migrate to one side or the other for that very reason. They can feed on that outside frame of honey in mid winter and free up cells for drone brood when required.

Select or create frames of drone brood comb that when placed in both outside slots total about 15 to 20 percent of the worker brood surface area. In my 9 frame brood chamber, with normally 5 frames of worker brood in the center, 2 frames of half or more drone cells comes out about right. Scale that up some for the 10 frame brood chamber.

Brood to the outside walls of the box has advantages of its own. For the bees, it is an advantage in the late winter, extreme cold snap. Any brood lost to chilling at the outside is drone brood. Loss of drone brood is less impact to the colony than loss of workers. For the beekeeper, there is less “stove piping”. With wall-to-wall brood nest warmth, the heat rise is spread out. As you know from your fireplace or campfire, heat rise tends to converge to the center. The same is true on a smaller scale at lower temperatures. When cluster warmth is distributed across the whole width of the brood chamber(s) the heat rise is more laminar. With the heat rise spread wider, the colony is more likely to maintain brood over more frames and less likely to “stove pipe”, as the brood nest expands upward.

A more regular advantage to the beekeeper is that the outside frame is easiest to remove. If you inspect for V mite by pulling some drone pupa or remove drone brood to reduce V mite population in their adolescence, the outside frame is where you want your drone brood. Time is money, and time saved is money in the bank. But you already know that.

Cycling drone brood to the freezer has gained some popularity in recent years. It’s a fairly benign V mite control measure that the organic honey producers can endorse. But to maintain colony morale, it’s not recommended that you remove all the drone brood at any one time. That’s just one more reason to distribute drone comb in both outside frames of the brood chambers.

Let’s close this out with my description of the subject creature. He is not very bright. Like some of our professional athletics, deep thinking is not a requirement for his job. His task is physical. He needs good vision, stamina, agility on the wing, and a tolerance for boredom at work. He doesn’t even need to be able to find his way home. He is welcome at any other colony he finds in his travels. I personally am quite fond of the big, ugly rascal. He supports my management system of requeening by supersedure.

Tip of The Month

Make it easy to separate boxes in the field. Insure that frame dimensions match the box dimensions. For top bee space boxes, top bars of frames should be recessed ¼ to 3/8 below the top edge of the box and bottom bars should be flush with the lower box edge. Bees put very little comb between frames properly spaced in the brood chambers. Note that deeps with frame rest rabbits sized for the stand-up rail leave too much space when the rail is not used.

Go the extra mile and taper the outside corner at the top of the box to leave a crack you can see for insertion of the hive tool. With a rasp or sander, take off a small amount of wood at the extreme outside of the top corners. A hive tool at both back corners will pop the propolis seal with a little leverage, and the upper box is ready to lift off.