During this month there is great activity among the insects. As the flowers bloom and the leaves appear, multitudes wake from their long winter sleep, and during this month pass through the remainder of their transformations, and prepare for the summer campaign. Most insects hibernate in the chrysalis or pupa state, while many winter in the caterpillar or larva state, such as the larvae of several Noctuidae and the "yellow-bear," and other caterpillars of Arctia and its allies. Other insects hibernate in the adult or imago form, either as beetles, butterflies or certain species of bees. It is well known that the Queen Humble bee winters under the moss, or in her old nest. During the present month her rovings seem to have a more definite object, and she seeks some deserted mouse's nest, or hollow in a tree or stump, and there stows away her pellets of pollen, containing two or three eggs apiece, which, late in the summer, are to form the nucleus of a well-appointed colony. The Carpenter bees (Ceratina and Xylocopa, the latter of which is found in abundance south of New England) are busy in refitting and tunnelling the hollows of the grape; while the Ceratina hollows out the stem of the elder, or blackberry. This little upholsterer bee carpets her honey-tight apartment, storing it with food for her young, and later in the season, in June, several of these cartridge-like cells, whose silken walls resemble the finest and most delicate parchment, may be found in the hollow stems of these plants. The Mason bee (Osmia) places her nest in a more exposed site, building her earthen cells of pellets of moistened mud, either situated under a stone, or in some more sheltered place; for instance, in a deserted oak-gall, ranging half a dozen of them side by side along the vault of this strange domicile. Meanwhile their more lowly relatives, the Andrena and Halictus bees, are engaged in tunnelling the side of some sunny bank or path, running long galleries underground, sometimes for a foot or more, at the farthest end of which are to be found, in summer, little earthen urn-like cells, in which the grubs live upon the pollen stored up for them in little balls of the size of a pea. Later in the month, the Gall flies (Cynips), those physiological puzzles, sting the leaves of our oaks of different species, giving rise to the strange excrescences and manifold deformities which deface the stems and leaves of our most beautiful forest trees. [Illustration: 227. Chrysophanus Thoe.[31]] 31 A: The lower side of the wings is figured on the right side of this and Figs. 228 and 229. [Illustration: 228. Argynnis Aphrodite.] [Illustration: 229. Melitaea Phaeton.]