As has been pointed out, the entrances of hives must be greatly reduced during the winter in order that the efficacy of the bottom packing may be preserved. It is desirable, however, that provision be made for larger entrances during the early fall and again in the spring. To provide conditions suitable at all times while the packing cases are on, the Bureau of Entomology has adopted a type of entrance which to some extent has been used previously in the North. Five 3/8-inch anger holes are bored in the ends of the packing case at a height that will allow for the thickness of the case floor, the bottom packing, and the thickness of the bottom of the hive. This usually is a little over 6 inches from the lower edge of the case ends. No alighting board should be placed at the outer entrance holes, as it is not needed and serves only to collect snow and ice.
To prevent the tunnels from getting out of alignment at the outer edge, a peg of the diameter of the holes is inserted through the outer hole for each hive and into the tunnel (see [fig. 2]). This peg is usually about 21/2 inches long. This leaves four auger holes, each three-eighths of an inch in diameter, for the bees to use as an entrance during the fall and spring, and during the colder weather a piece of section material or a small board is tacked over three of the holes. (See [fig. 3].) This gives in winter a single hole for an entrance, three-eighths of an inch in diameter. This provides a place for the bees to remove their dead, a place for flight on moderately warm days, and also provides adequate ventilation for the hive while the bees are confined without an opportunity for flight. However, the size of entrance should not be discussed without warning beekeepers that unless adequate packing is provided, such a small entrance may result in the death of the colony. Furthermore, a poorly packed colony will not be able to carry out the bees as they die, and the death rate will be higher; and these things combined may result in an accumulation of dead bees at the entrance, which will serve to suffocate the remaining bees. A colony that is well packed, however, is able to remove all dead bees as fast as they die, and there will never be an accumulation on the floor of the hive. Furthermore, a well-packed colony does not need so large an entrance for ventilation as does one that is not packed or which has not enough packing. If snow drifts over the small entrance here described, the beekeeper need have no anxiety, for the bees can still receive adequate ventilation. If a crust of ice closes the entrance it will be well to break it, but usually the escaping heat will melt this ice before any damage is done.
Fig. 5.—Map of the eastern United States indicating average date of first killing frost in autumn. On this the zones for winter packing are based. No packing is recommended in zones A and B.>
WINTER SCHEDULE.
Great confusion has existed among beekeepers as to the right time to pack the bees for winter, and especially as to the right time to remove the packing in the spring. It is quite possible to give definite directions for both procedures and to place the recommendations on a firm foundation by basing them on weather phenomena. The maps (figs. [5] and [6]), showing the time of the first average killing frost in the fall, serve as a basis for the recommendations for each of the zones into which the map of the eastern United States is divided. Perhaps it will be a matter of surprise to beekeepers in parts of the South to see that, so far as the wintering of the bees is concerned, they are as far north as beekeepers who live many miles farther toward the pole.
The lines on [figure 5] indicate the average dates of the first killing frost in the fall, and these dates, given at the ends of the heavy lines, are of direct value to the beekeeper as giving the proper time for putting on the winter cases. The average dates of the last killing frost in the spring do not show exactly the same lines on the maps, but the differences are not sufficiently great to justify the use of a separate map for this purpose. The authors have chosen therefore to divide the country into the zones indicated, and the recommendations given below apply to each of the zones shown.
On account of the variations in elevation, it is impossible to carry these lines into the Rocky Mountain region, but as packing is just as necessary in the West as in the East, [figure 6] is inserted to indicate roughly the time for the putting on of the packing in the fall. The dates in this map are the average dates of the first killing frost. By consulting Table I the beekeeper of the West may learn the time advised for the removal of the packing, by placing his locality in its proper zone, on the basis of the first killing frost.