The _Phryganea rhombica_ (Figs. 415, 416, 417) furnishes its case with bits of wood or grass, arranged as shown in Fig. 418. Some species arrange these bits of wood and glass in spiral, others in parallel series. The _Phryganea flavicornis_ covers its dwelling with little shells. "These kinds of dress," says Réaumur, "are very pretty, but they are also excessively singular. A savage who, instead of being covered with furs, should be covered with musk rats, moles, or other entire animals, would have on an extraordinary costume; this is in some sort the case with our larvæ." Other _Phryganeæ_ employ for constructing the case which serves them as a dwelling sand and small pebbles; each species always employing the same materials, unless they are entirely deprived of these and obliged to employ others. These cases protect the larvæ against the voracity of their enemies. The larvæ have a scaly head; and the three first rings of their body are harder than the rest. They live in water, and breathe by means of branchious sacs, arranged on the abdomen in soft and flexible tufts. They eat everything that is presented to them: leaves, and even insects and the larvæ of their own kind. The pupæ are motionless. They stay about a fortnight in their case, the orifice of which is closed by gratings of silk, then break through the gratings, and leave their prison. In this state (Fig. 419) they swim on the water until they meet with an object to which they can attach themselves, and so get out. Then they swell till they crack their skin over the back, and the perfect insect emerges. The _Phryganea pilosa_ (Fig. 420) is of a yellowish grey, with hairy wings, little adapted for flying. These insects do not eat, and never leave the neighbourhood of the water. During the day they rest on flowers, on walls, or on the trunks of trees, their wings folded back, and their antennæ together. In the evening they fly in dense swarms over streams and ponds. They are attracted by light, as are many nocturnal insects; and are sometimes found in great numbers on the lamps on the quays in Paris. [Illustration: Fig. 419.--Pupa of Phryganea pilosa, magnified.] [Illustration: Fig. 420.--Phryganea pilosa.]