78 ELEMENTARY LESSONS ON INSECTS 



They differ correspondingly in their transformations. 

 When the larva is grown and the last larval skin is cast, out 

 of it comes the pupa. Then appear the organs of the adult, 

 long legs and antennae and wings, etc., but not at once in 

 condition for use. They are folded closely about the body 

 and so remain during a long resting period. 



All feeding is done for life in the larval stage — the stage 

 of growth and fat accumulation. The pupa is the stage of 

 making over. The adult is the stage of reproduction, mating 

 and egg-laying. 



Let us now follow the life history of a caddisfly. The net- 

 maker, Hydropsyche, is one that can be found about any 

 clean brook, where their larvae dwell in the riffles. The 

 oblong brownish eggs are laid on the underside of sticks or 

 stones, the female creeping down under water to deposit 

 them. She lays them on their sides in dense patches one 

 layer deep, in part in regular rows, and covers them over with 

 a thin transparent gelatinous secretion. The patches, often 

 as large in area as a penny, and chocolate tinted, are easily 

 found in their season by lifting and overturning stones. 



The larvae that hatch from these eggs construct for them- 

 selves fixed shelters at the edge of the current. They spin 

 silk and use it to attach bits of sand and rubbish all over the 

 outside in making these shelters. Then they spin delicate 

 nets of silk at the head end, next the current. These are 

 beautiful fine-meshed nets, attached at their edges below 

 and by stay lines above, that swing, baglike, down stream. 



