Before deciding whether or not the bees are to be wintered in a cellar, several factors should be considered, the chief of these being (1) the winter climate, (2) the kind of winter stores, and (3) the location of the apiary as regards wind protection.

WINTER CLIMATE.

In any locality where the average temperature of the winter months falls below 25° F. (zone 1) cellar wintering may be practiced with profit, and in localities where the average temperature of these months falls as low as 15° F. (zone 2) cellar wintering is much to be preferred. Figure 1 shows the boundaries of these zones for the United States for the month of January, which may be taken as typical of the winter months. It will be noted that these zones do not follow parallels of latitude. As was pointed out in the bulletin of the department on outdoor wintering,[2] it is quite possible to protect bees in zone 1 sufficiently to winter them outdoors, but if a proper cellar is provided, if conditions within the cellar are correct, and if the stores are good and the colonies are strong, just as good results may be obtained from cellar wintering.

In zone 1 the average temperature of the outside air during the mouth of January is 25° F., or lower in the more northern parts of the zone. This means that in colonies wintered outdoors the bees are compelled to overcome this degree of cold at all times during the coldest part of the winter. If they are so well packed that the heat which they generate is lost slowly, they are able to generate sufficient heat to make the interior of the hive warm enough to allow them to break their cluster as is necessary. In zone 2, however, the bees will be compelled to generate heat sufficient to overcome the more severe cold of that zone, and this calls for the expenditure by the bees of so much more food and vitality that it is more economical to put them in a good cellar during the months of the most severe cold, and cellar wintering is therefore preferable.

CHARACTER OF WINTER STORES.

In localities where the stores for the bees gathered during the latter part of the summer are not of the first quality, it is safer to winter the bees outdoors. This is a large factor in the placing of the zones shown in figure 1, for it is quite common in the region south of zone 1 for the full honey to be of inferior quality. It is extremely fortunate that in both of the zones shown the stores available in winter are usually of the finest quality. As will be shown later, it is highly important that the beekeeper pay special attention to the character of the stores in the hive at the beginning of the winter, and if they are not as good as they should be, this deficiency should be corrected.

LOCATION AS REGARDS WIND PROTECTION.

In zone 1, if the apiary is so badly located that the winter winds are severe, the beekeeper will do well to winter in a cellar, although, as will be shown later, it is not best to choose such a site for the apiary even during the rest of the year.