Water-Caterpillars, Eruc aquaticte, L. are thus called from their living under water. They feed on aquatic plants, and respire by their stigmata in the same man-ner as the common caterpillars of the garden.

There are, acccording to Reaumur, two varieties of these insects, the one on the Potamogelon, or pondweed ; the other upon the Lenticula, or duck-meat: the first of these is the larger; and, as its operations are more easily distinguished, it is better known than the other. Though strictly an aquatic animal, it does not delight in the water, and is extremely solicitous to avoid wetting itself. It is produced in the same maimer as the land-caterpillar, from an which the parent butterfly deposits on the leaf of a certain plant, out of which the insect, as soon as it is hatched, gnaws a piece of a circular form. This it carries to another part of the same leaf, and places it so as to construct a cavity in which it may safely lodge. It " then fastens down the piece to the larger leaf, by silk of its own spinning, leaving holes at certain distances, through which it may push its head, and prey upon the adjoining leaves : these are naturally so smooth, that they are seldom wetted ; and, as often as its habitation becomes too small, the insert makes others successively, each being adapted to its periodical size, till it undergoes the usual changes into a butterfly. In this state, as soon as its wings are dry, it leaves the water, never to return again.

Wood-Caterpillars, Eruce sylvestres, are thus denominated, because they live, contrary to the generality of caterpillars, under the bark, in the trunk, branches, and roots of trees, and sometimes in the body of the fruit. They are produced from eggs deposited on the surface; and eat their way farther, as soon as they are hatched.

Some of these caterpillars leave their abode in order to change into their chrysalis, and thence into their butterfly state; but most of them remain there, and pass through, all their changes. These inserts would increase to an immense number, were they not destroyed in a similar manner with the common caterpillars, by a species of worms, that insinuate themselves into the fruit or tree inhabited by the former, which successively become their prey.

Various experiments have been tried to extirpate these pernicious vermin; but none has been attended with more success than that of lighting small tires near trees, about sun-set, into which the) will eagerly fly; and thus, by burning their wings, meet with inevitable destruction.