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 2-1/2 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.
[Illustration: 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.]