When a thaw occurs, everything, both in and out of doors, has a great deal of dampness about it. The combs of a hive are not exempt from this, so that it is advisable to have slight upward ventilation in winter. Holes the size of a pin's head allow of the escape of a good deal of bad air, which is generated by the exhalations of the bees, as well as by the dampness before referred to. These holes, being small, do not create sufficient draught through the hives to be pernicious; if closed up by propolis, they are readily reopened with a pin. With wooden hives in winter, a bell-glass is often found to be useful; it should be placed over the hole in the crown-board, with a zinc trough to receive the condensed moisture. In summer, bees do much towards ventilating their own stock-hives. The observant apiarian will not fail to remark how, on a warm day, several of the little creatures will stand at the entrance, with their abdomens sightly raised and their twinkling wings in rapid motion, producing a current of air inwards; while another set are engaged in like manner, driving the bad air out, so that a supply of pure oxygen is conveyed to the crowded inmates. In this fanning operation their wings vibrate with such rapidity, that their shape is as indistinct as are the spokes of a wheel when revolving in rapid centrifugal motion. This important office entails great physical exertion on the part of the bees, and they relieve each other in detachments. Fine colonies are sometimes destroyed by the entrance-way becoming stopped by some impediment or other, and care is requisite to keep a watch, that so fatal a catastrophe does not happen, because the bees (_unless where very ample ventilation is given_), excited by their imprisonment, make matters worse, by raising the temperature of their hive to such a pitch, that the combs melt from their foundations, and the bees themselves are suffocated, presenting, alas! a most woful spectacle to witness.