THE TRICHOPTERA. 19 



house. Some larvae have fixed cases, others move freely about by protruding the head and first two 

 thoracic segments from the mouth of the case, when they are able to walk upon the feet attached to 

 those segments. Their hold of the interior of their dwelling is secured in part by the legs of the 

 third pair, which are often much elongated, and in part by certain more or less hook -like appendages 

 to the apex of the abdomen. The long hind legs are mainly instrumental in drawing the larva 

 back within its case, which they can do very rapidly should any danger threaten, the Caddis-worms, 

 aii they are commonly called by anglers, being not unwelcome articles of food to fishes and other 

 predaceous aquatic animals. We must add that the larvae of different species live in all sorts of 

 water, from the most stagnant pond to the mountain torrent, and that their food consists chiefly of 

 aquatic plants, although occasionally they will not disdain animal food. 



When full grown, the larva prepares for its change to the pupa state by shortening its case, 

 and closing both apertures of its dwelling with silk and vegetable materials or small stones, but 

 so that the water still has free access to the interior, the closure being sometimes effected by a 

 circular grating of very ingenious construction. The case is also attached and often strengthened 

 at this time. The change to the pupa then takes place within the case, and after a longer or 

 shorter time the pupa breaks out of its dwelling and makes its way out of the water, in order 

 to cast off its last covering, and give birth to the perfect insect 



The Phryganeidae include the largest species of the order, although found only in northern 

 regions. Thus Neuronia jjhalcenoides, a north European species, which occurs in Northern 

 Asia, but does not extend its range so far west as Britain, measures nearly an inch long in body, 

 and has an expanse of wing of about two inches and a half. It is a black insect, with white 

 wings, variegated with numerous black spots. One of the largest British species is the Phryganea 

 grandis, which measures four-fifths of an inch in length, and over two inches in expanse of wing. 

 It is an abundant insect, of a brown colour, with yellow rings on the antennae, and the anterior 

 wings ash-coloured, clouded with brown. The larv<e of this group inhabit quiet waters, ponds, 

 lakes, &c. Their cases are cylindrical, and formed of vegetable materials, such as fragments of 

 leaves, fibres, &c., usually arranged in a more or less spiral manner. 



The Limnophilidae are a very extensive group, many species of which occur in Britain. The 

 larvae live both in standing and running water, and some of them even in torrents. Their cases are 

 very varied in structure. LimnopkUus rhombicus (see figure on p. 18) forms a case of vegetable 

 fragments, such as detached fibres, portions of grass, and bits of moss, which are arranged transversely, 

 so that the outer surface presents a rough, bristling appearance. L. flavicornis (see figure on p. 18) 

 uses a variety of materials in the construction of its case, such as fragments of wood, shells, and small 

 stones, but entire shells, often with the living inhabitants, are the most common. Another species 

 (L. stigma) employs small round pieces of the leaves of willows, which are laid one over the other, 

 while L. lunatus (see figure on p. 18) makes a case of sand grains mixed with vegetable matter, and 

 then attaches to the outside larger pieces of wood, and even long twigs, which may project beyond both 

 ends of the case. This species lives in standing water. The larva of L. politus takes up its abode 

 in a fragment of reed, which it bites to the right length, and then attaches long twigs to it at both 

 ends, and that of L. vittatus makes a curved cylindrical tube of fine sand. The larvae of the 

 genus Stenophylax live in running water, and often in mountain torrents. Their cases are 

 generally tubular, formed of fine sand, and temporarily attached to large stones, or the larvae 

 keep their cases free, and shelter themselves behind stones at the bottom of the water. Thamastes 

 dipterus, a Siberian species, is remarkable for having the posterior wings quite rudimentary, and 

 the maxillary palpi three-jointed in both sexes. The species of Enoicyla have the females nearly 

 wingless, the wings being represented only by triangular scales. The larvae live among moss at the 

 roots of trees, and often at a great distance from water. They make a cylindrical case, composed 

 of fine sand-grains, usually more or less mixed with morsels of bark and other vegetable matters. 

 Parthenogenesis is believed by Mr. McLachlan to occur in some species of Apatania, of which no 

 males have ever been seen. Apatania muliebris, an inhabitant of some parts of the South oi 

 England, is one of these. 



Of the Sericostomidae, the larvae generally inhabit streams, and dwell in a free case, which 

 is usually formed of sand and small stones. In some, such as the species of Goera and Silo, the 



