CAD'DICE, or CAD'DICE-FLY (phryganea), Linnten genus of insects of the order neu roptera, a family in subsequent entomological systems, and constituted by Mr. Kirby into a distinct order, trichoptera (Gr. hairy-winged). The caddiee-flies certainly differ in important particulars from the other neuropterons insects, and exhibit points of resem blance to the lepidoptera. They have no mandibles, and the maxilla and lower lip are membranous and united; the head is small, with prominent eyes, and two additional small simple eyes situated on the forehead; the antenna are long and bristle-like, com posed of very numerous indistinct joints. Both wings and body are generally very hairy, and the wings, when at rest, are raised, and meet above the back like those of butterflies, from which, however, they differ very much in form, being much more elongate: the legs are long. Caddiee-flies are extremely active, particularly in the even ing and at night, when the smaller species often fly in great numbers above streams and ponds. These insects are most interesting, however, on account of their larvae, of which the larger kinds are the well-known caddice-tcorms, or cad-bait of anglers. They are of a long, almost cylindrical form, the head and first three segments hard, the remainder —the abdominal segments—soft. To the thoracic segments are attached the feet, six in numlAr, as in the perfect insect. The larva lives always in water, feeding on aquatic vegetables. It spins by its mouth silken threads, by means of which, together with a viscid substance, it attaches together—and often in a very symmetrical manner, and with interesting peculiarities which differ in the different species—small hard substances, such as small stones, bits of stick, or small shells, even although they happen to contain living inmates, and thus constructs a case for itself, in which its soft body is protected, and from which only the head and hard thoracic segments are voluntarily protruded.
When it changes into the pupa state, in which it differs little from the perfect insect, except in the imperfectly developed wings, it fixes its case to some solid substance beneath the water, and closes the two extremities with a kind of grating, which admits the free passage of water, necessary for respiration. Before assuming tile perfect form, the pupa of the larger species breaks out of its case by means of a pair of hooks on the forepart of the head, and actively by means of the hind legs, or crawls by the other two pair. Many of the smaller species their pupa case to the surface of the water, and there take wing from it as from a boat. The species of caddice-fly are very numerous, and they are said to be more so in the n. than in the s. of Europe. About 200 British species have been describcd.—Thc angler looks for cad-bait about the edges of streams and under stones, or on the stalks of water-cresses, and other aquatic plants. As a bait for angling, the caddice is almost as deadly as the May-fly, and more so, in clear running streams, than the ordinary worm; the usual-sized bait-hook is used, upon which two of the baits are fixed, the angler proceeding exactly as in ordinary worm fishing.