In May last (1829), we found on the walls of Greenwich Park a great number of caterpillars, whose manners bore some resemblance to those of the grub described by M. Réaumur. (J. R.) They were of middle size, with a dull-orange stripe along the back; the head and sides of the body black, and the belly greenish. Their abodes were constructed with ingenuity and care. A caterpillar of this sort appears to choose either a part where the mortar contains a cavity, or it digs one suited to its design. Over the opening of the hollow in the mortar it builds an arched wall, so as to form a chamber considerably larger than is usual with other architect caterpillars. It selects grains of mortar, brick, or lichen, fixing them, by means of silk, firmly into the structure. As some of these vaulted walls were from an inch to an inch and a half long, and about a third of an inch wide and deep, it may be well imagined that it would require no little industry and labour to complete the work; yet it does not demand more than a few hours for the insect to raise it from the foundation. Like all other insect architects, this caterpillar uses its own body for a measuring-rule, and partly for a mould, or rather a block or centre to shape the walls by, curving itself round and round concentrically with the arch which it is building. We afterwards found one of these caterpillars, which had dug a cell in one of the softest of the bricks, covering itself on the outside with an arched wall of brick-dust, cemented with silk. As this brick was of a bright-red colour, we were thereby able to ascertain that there was not a particle of lichen employed in the structure. The neatness mentioned by Réaumur, as remarkable in his moss-building caterpillars, is equally observable in that which we have just described; for, on looking at the surface of the wall, it would be impossible for a person unacquainted with those structures to detect where they were placed, as they are usually, on the outside, level with the adjoining brick-work; and it is only when they are opened by the entomologist, that the little architect is perceived lying snug in his chamber. If a portion of the wall be thus broken down, the caterpillar immediately commences repairing the breach, by piecing in bits of mortar and fragments of lichen, till we can scarcely distinguish the new portion from the old. _CHAPTER X._ CADDIS-WORMS AND CARPENTER-CATERPILLARS. [Illustration: Leaf Nest of Caddis-Worm.] [Illustration: Reed Nest of Caddis-Worm.]