Insects in all stages of their growth are creatures of the warmth; the heat is the motive power that makes them go; when this fails, they are still. The katydids rasp away in the fall as long as there is warmth enough to keep them going; as the heat fails, they fail, till from the emphatic "Katy did it" of August they dwindle to a hoarse, dying, "Kate, Kate," in October. Think of the stillness that falls upon the myriad wood-borers in the dry trees and stumps in the forest as the chill of autumn comes on. All summer have they worked incessantly in oak and hickory and birch and chestnut and spruce, some of them making a sound exactly like that of the old-fashioned hand augur, others a fine, snapping, and splintering sound; but as the cold comes on, they go slower and slower, till they finally cease to move. A warm day starts them again, slowly or briskly according to the degree of heat, but in December they are finally stilled for the season. These creatures, like the big fat grubs of the June beetles which one sometimes finds in the ground or in decayed wood, are full of frost in winter; cut one of the big grubs in two, and it looks like a lump of ice cream. Some time in October the crows begin to collect together in large flocks and establish their winter quarters. They choose some secluded wood for a roosting-place, and thither all the crows for many square miles of country betake themselves at night, and thence they disperse in all directions again in the early morning. The crow is a social bird, a true American; no hermit or recluse is he. The winter probably brings them together in these large colonies for purposes of sociability and for greater warmth. By roosting close together and quite filling a tree-top, there must result some economy of heat. I have seen it stated in a rhetorical flight of some writer that the new buds crowd the old leaves off. But this is not true as a rule. The new bud is formed in the axil of the old leaf long before the leaves are ready to fall. With only two species of our trees known to me might the swelling bud push off the old leaf. In the sumach and button-ball or plane-tree the new bud is formed immediately under the base of the old leaf-stalk, by which it is covered like a cap. Examine the fallen leaves of these trees, and you will see the cavity in the base of each where the new bud was cradled. Why the beech, the oak, and the hickory cling to their old leaves is not clear. It may be simply a slovenly trait--inability to finish and have done with a thing--a fault of so many people. Some oaks and beeches appear to lack decision of character. It requires strength and vitality, it seems, simply to let go. Kill a tree suddenly, and the leaves wither upon the branches. How neatly and thoroughly the maples, the ashes, the birches, the elm clean up. They are tidy, energetic trees, and can turn over a new leaf without hesitation.