To get the value of bottom packing it is absolutely essential that the entrance be reduced, but it need not be closed. In a long series of temperature readings on hives packed for several winters, the authors were able to keep a temperature of 50° F. on the bottom boards of packed hives directly behind the entrance openings. Those who have condemned bottom packing have labored under the mistaken notion that it is impossible to prevent currents of cold air through the entrance. This is entirely possible if the entrances are adequately reduced. The conclusion to be drawn from the experiments performed is that unless the bottoms of hives are well packed, the beekeeper ought not to imagine that he has packed his hives at all well. [Illustration: Fig. 2.--The winter packing cases used in the Bureau of Entomology apiary: _a_, Detail of tunnel to hives. In the specifications given in this Bulletin (p. 9) provision is made for room for a third hive body to be added in the spring.] THE PACKING CASE. There is no virtue in any special type of case, but in all types there are a few points which must be observed. There must be provision for abundant packing on the top, bottom, and sides, the entrances must be small, the case must be rain-proof, and the construction of the case should be such that it may be taken apart and put together easily. The parts of various cases used in one series of apiaries should be interchangeable. The authors have refrained in the past from giving explicit directions for making a winter packing case for fear that some beekeepers might think that there may be peculiar virtue in the case used and recommended by the department (fig. 2). So many beekeepers, however, have written for exact dimensions for making the case used in the apiary of the Bureau of Entomology that it is considered best to give these in this bulletin. In order that protection adequate for bees in a climate such as that of Washington may be provided, 4 inches of packing below the bottom board, 6 inches on all sides, and at least 8 inches on top are desired. There is advantage in packing several colonies together, in order that they may warm each other and to reduce the cost of the case and the labor of putting it on. The bureau, therefore, has adopted the four-colony type of case which has been much used for years in all parts of the country. In this case, two colonies face east and two west. Provision is made for wintering all colonies in two full-depth hive bodies.