3^8 



TRANSFORMATIONS OF INSECTS. 



soft skin of the abdomen is terminated by two hooks, which 

 anchor the insect in its dwelHng. 



When about to undergo their metamorphosis the larvae fix 

 their tube or case upon something and close up the ends. The 

 nymphs have the same kind of respiratory organs as the larvae, 

 and in order to enable its successor to breathe, the larva closes 

 the tube with a sort of open-work fence, which, whilst it prevents 

 any intrusions, allows the water to flow in and out. 



The nymph has rudimentary wings, and resembles the larva 

 more than the imago. 



Hydropsyche atomaria. LARVA, imago, shelter, PUPA, AND CASE. 



The caddis fly, with yellow or fawn-coloured antennae {Phry- 

 gmica flavicornis), when in the larva state, forms its case with large 

 bits of wood. Phryganea rhoinbica chooses the sprigs of aquatic 

 plants, and Phryganea fusca makes a central tube of tiny pieces 

 of stone, and adds long straws and shreds to the outside. 



The tubes of these species are represented in the engraving. 



Some caddis flies, when in the larval state, form shelters which 

 are not movable, and which afford homes to several individuals. 

 The species of Hydropsyche have larvae with branchial filaments 

 or gills attached to the abdomen, and their metamorphosis into 

 the pupa is complete. 



