184 INSECT TRANSFORMATION 



is free, its wings possessing only radial and median tracheal 

 trunks. 



Order 18. Trichoptera 



The Trichoptera (caddis-flies) have no mandibles, the 

 maxillae and labium being adapted for sucking. The hairy 

 wings are membranous, the forewings being long and narrow, 

 the hindwings shorter and broad, with a folding area ; there 

 is a full set of longitudinal nervures in both wings but cross- 

 nervules are few. Abdominal cerci are absent. 



The larvae (" caddis-worms ") of Trichoptera are aquatic. 

 They have strong biting mandibles and well-developed, clawed 

 thoracic legs. The body-cuticle is comparatively feeble, as 

 these larvae are sheltered in cases which they construct by 

 spinning together fragments of plants, stones, etc. The 

 " free " pupa is provided with strong biting mandibles ; its 

 wing has only two tracheal trunks : the radial and a cubital 

 or an anal. 



Order 19. Lepidoptera 



The Lepidoptera (moths and butterflies) have (except in 

 one most primitive group) no mandibles and no maxillary 

 laciniae, the maxillary galeae long and flexible forming a 

 sucking trunk or proboscis. The scale-covered wings have a 

 nervuration mainly longitudinal. The abdomen has no cerci, 

 and the genital armature though well-developed is incon- 

 spicuous. 



The larvae of Lepidoptera are of eruciform type (caterpillars), 

 with short feelers, strong biting mandibles, jointed thoracic 

 legs and abdominal prolegs (five or fewer pairs) usually un- 

 jointed and with terminal hooks or spines. The pupa is very 

 exceptionally " free " and mandibulate ; usually it is more 

 or less obtect. The pupal wing has a complete set of tracheal 

 trunks. 



Two sub-orders of the Lepidoptera may be recognized. 



Sub-Order i. Homoneura 



In this more primitive section the hindwing has, like 

 the forewing, five radial nervures ; here are included the 



