Having completed their period of feeding, which they do in about four weeks, the caterpillars attach themselves by means of their tails to a fence-rail, a window-ledge, or some such place, and pass into the chrysalis state, which is accomplished in about four days. In this condition they present an odd-looking appearance. The head will be found to be deeply notched, or furnished with two ear-like prominences. The sides are very angular. In the middle of the thorax there is a thin projection, somewhat like a Roman nose in profile, while on the back are two rows of very sharp tubercles of a tawny color, which contrast very markedly in coloration with the dark-brown of the rest of the chrysalis. Fifteen days, when the weather is favorable, are sufficient for the development of the imago, or butterfly. As maturity approaches, the chrysalis-shell becomes quite soft, and the efforts of the imago to free itself from this covering are facilitated by the ejection of a blood-red fluid, which rots the case, while it acts, at the same time, as a lubricant to the emerging butterfly. When these caterpillars are very abundant, as was the case in the vicinity of Germantown some twenty-five years ago, every fence-rail was hung with chrysalids, as many as a dozen being found upon a single rail. The caterpillars even climbed up the sides of the houses and suspended themselves from the window-ledges and the edges of the overhanging shingles. When the butterflies emerged, great blotches of the fluid bespattered the fences and houses as though the clouds had rained great drops of blood. The willows and poplars were alive with the caterpillars, and even the maples were overrun when there came a scarcity of the leaves of the natural food-plants. Green caterpillar-hunters were everywhere plentiful, and the writer could have taken hundreds of specimens, but these highly-useful beetles made a very sorry attempt in holding the enemy in check. Two broods of the caterpillars are raised, one in June and the other in August, but the agencies by nature employed for their destruction so effectually accomplish their mission that hardly a season brings to my notice a dozen full-grown larvæ. _Vanessa antiopa_, as this species is called by the scientific student, or Mourning-Cloak by people and amateurs, is generally found through the whole of North America. In England, where it is popularly called the Camberwell Beauty, because specimens were first taken near Camberwell, it is the rarest of butterflies; while on the Continent, as in this country, it is a very plentiful insect. LEAF-CUTTER BEE. Few hymenoptera of the family of bees are so little known as the Megachilidæ, or Leaf-cutters. They are stout, thick-bodied insects, with large, square heads, and armed with sharp, scissors-like jaws, which admirably fit them for the work they have to do in preparing materials for the building of their homes.