i6o 



INSECTS. 



prominent eyes, and usually also three ocelli, placed on the forehead. With the 

 exception of the palpi, their mouth-organs are feebly developed. Their legs are 

 long, and possess five-jointed tarsi ; and the tibiae are generally furnished with 

 spurs, whose number and disposition are of considerable value in distinguishing 

 the genera. These insects fly chiefly in the evening or at night, and, attracted by 

 the light, frequently enter houses ; some of the smaller species flying in swarms 

 over water. The larvae, with few exceptions, are aquatic in their habits ; some 

 being carnivorous, although most feed on vegetable matter. Found in streams, 

 lakes, and ponds, or any piece of water in which plants grow, caddis- worms, as the 



VAKIOUS FORMS OF CASES MADE BY CADDIS-FLY LARV.E. 



1-5, Cases composed of sand and pebbles ; 6, A case made of small snail-shells ; 7-10, Cases made of 



different parts of plants. 



larvae are called, are well known to anglers, by whom they are frequently used as 

 bait. The eggs from which they are hatched are laid sometimes in the water, or 

 on aquatic plants or trees overhanging water. Females have occasionally been 

 captured with a coating of dry mud on their abdomen, showing that they had gone 

 to some muddy pool to lay their eggs. The cases, made out of all sorts of materials, 

 with which many of the larvae surround their bodies, have long been objects of 

 interest to the naturalist. Some larvae pick up bits of sticks and leaves, grains of 

 sand, and fragments of shells, or whatever else comes handiest, and fasten them 

 together in a rough sort of fashion ; but many exercise a choice in the selection of 

 materials, and exhibit great dexterity and neatness in piecing them together. The 



