CLASSIFICATION 317 



three to five segments. In a minority of the families 

 there is a headed larva and the orthorrhaphous type 

 of pupa. Most Brachycera have headless maggots as 

 their larvae ; the final larval cuticle is not shed but 

 hardens and contracts to form a protective case 

 (puparium) for the pupa. The puparium (Fig. 54) 

 splits open by the breaking away of an anterior 

 rounded lid to allow for the emergence of the fly 

 (Cyclorrhapha). 



Order 21. APHANIPTERA 



The Fleas are laterally compressed, parasitic, wingless 

 insects with elongate piercing and sucking jaws adapted for 

 drawing blood from their vertebrate hosts. They have 

 mandibulate and legless cruciform larvae (Fig. 67, b). 



Order 22. STREPSIPTERA 



These are very small insects parasitic on other insects 

 (mostly Hemiptera and Hymenoptera). The males are 

 active and winged, the hindwings being membranous, and 

 the forewings reduced to balancers. The females are 

 wingless and passive, remaining in the bodies of their host- 

 insects. They develop with a hypermetamorphosis, a 

 minute active campodeiform larva transforming into a 

 legless parasitic grub. 



Order 23. HYMENOPTERA 



The members of this large order have biting mandibles 

 and the labium adapted for sucking liquids. The fore- 

 wings are markedly larger than the hindwings, and the 

 nervuration is specialised so as to form a series of small 

 areolets on the wing area. The first abdominal segment is 

 joined to the thorax. Cercopods are present and the female 

 has a strong ovipositor. The larva is cruciform and the 

 pupa free. 



