Nerve-winged Insects; Scorpion-flies; Caddis-flies 227 



flows swiftest. They are carnivorous, feeding upon the nymphs of stone- 

 flies, May-flies, and other insects. When about two years and eleven months 



Imd 



nan: 











Fig M,-Head of larva, pupa, and adult of dobson-fly, Corydahs <:<-r««ta, showing 

 development of the mouth-parts of the adult within the mouth-parts of the lan-a. 

 \ head of a larva with its cuticle dissected away on the nght-hand side, reveahng 

 ih'e pupal parts; B, head of male pupa with cuticle dissected away on nght-hand 

 side revealing developing imaginal parts; C, head o female pupa with cuticle 

 who Iv removed, showing imaginal parts; D, head of adult male, mi mandib o, 

 mx maxilla; /:'., labmm; lb., labrum; ant., antenna; /./:., larval head-wall; ph., 

 pupal head-wall; Ra., galea; U.p., labial palpus; mx.p., maxillary palpus. Any 

 of these terms may be prefi.\cd by /, larva; p, pupa; or t, imago. 



old the larva leaves the water, anil makes a cell under a stone or some other 

 object on or near the bank of the stream. This occurs during the early 



