i86 INSECT TRANSFORMATION 



larva is a headless maggot with mouth-hooks. The last 

 larval cuticle hardens to form a puparium from the front 

 end of which a round lid splits off to allow the escape of 

 the imago. 



Order 21. Aphaniptera 



The Aphaniptera (fleas) are laterally compressed, wingless 

 insects, parasitic in the adult state on vertebrates whose blood 

 they draw by means of highly-specialized elongate piercing 

 and sucking jaws, both maxillary and labial palps being 

 developed. 



The larvae of fleas are of an eruciform, legless type with 

 well-developed head provided with biting mandibles. The 

 pupa is free 



Order 22 Sirepsiptera 



The Strepsiptera are minute insects parasitic (except the 

 free-flying males) on various Hymenoptera and Hemiptera. 

 The male has complex feelers, slender mandibles and reduced 

 maxillae, a very short prothorax and elongate metathorax ; 

 the forewings are club-shaped balancing organs, the hindwings 

 broad and membranous with simple longitudinal nervures and 

 no cross-nervules. The abdomen has ten segments with 

 prominent genital armature. The female has all the appen- 

 dages vestigial and is wingless ; the head is fused with the 

 thoracic segments and the abdomen shows normal segmenta- 

 tion ; she lives within the body of the host insect. There is 

 a remarkable hyper-metamorphosis. Active campodeiform 

 larvae with clawless sucker-feet emerge from the front end of 

 the mother's body, and enter the larva of the host, where they 

 become legless grubs with degenerate head. The free pupa is 

 enclosed in a puparium, whence the female never completely 

 emerges. In some males a pre-pupal stage with wing-rudi- 

 ments can be recognized. 



Order 23. Hymenoptera 



The Hymenoptera have typical biting mandibles and a 

 suctorial labium, both pairs of wings usually developed, 



