^o. 2242. MORPHOLOGY OF THE 8TREPSIPTERA— PIERCE. 421 



4. The male Strepsipterous head is characteristic. 



a. The eyes are large, bulbous, with the oiumatidia separated by partitions, 

 b. The auteuuae vary from seven- to four-jointed and always have at least 

 the third and the last joints flabellately produced and covered with 

 sensitive organs. 

 c. There is neither labrum nor labium, and the pharyngeal area is broadly 

 exposed. 

 d. The mandibles are ensiform and distant from the buccal opening. 

 e. The maxillae are two- or three-jointed, resembling palpi, and also 

 distant from the buccal opening. 



5. The thorax has 10 segments, with the tenth serving as a flap over 

 the extended ninth. The tenth bears the anal opening. The ninth 

 has at its extremity an everted acute chitinous tube, with a subapical 

 pore for the extrusion of the penis. 



6. The female is permanently inclosed in the last larval skin and 

 remains in the body of its host. It is a mere sac of eggs, larviform 

 in appearance and legless. 



a. The head and thorax are united to form a cliitinous disk known as the 



cephalothorax. This has only a mouth opening, a pair of mandibles and 



one or two pair of spiracles. It is the only exposed part of the body. 



b. Between the head and thorax on the venter of the cephalothorax is the 



opening of the brood canal, which extends between the female and 



the uncast skin at least to the third and sometimes to the sixth 



segment. 



c. Entering this canal are from five to three unpaired median tubes through 



which the young escape into the brood canal and thus leave the parent. 



7. The male pupa is of the form of the Hymenopterous pupa. It is 

 contained within a puparium formed by the chitinization of the last 

 larval stage. The puparium shows definite homologues of all ap- 

 pendages. The head forms a cap or cephalothorax, which is burst off 

 when the male emerges. 



8. The female has no pupal stage. 



9. The larvae are legless, except in the first stage. 



10. The first larva is active, hexapodal, with long anal stylets, 

 ivith backward pointing mandibles and peculiar internal chitiniza- 

 ;ion surrounding the mouth. 



Internal anatomy. 



11. The intestines in later stages are closed behind. 



12. The nervous system is reduced to three ganglia, supraoeso- 

 phageal, thoracic, and ventral. Even in the degenerate female there 

 is a large brain. 



13. The malpighian vessels and cutaneous glands are absent or 

 greatly modified. 



Biology. 



14. Always hypermetamorphic : 



a. Hexapod first larvae. 



b. Legless degenerate later larvae. 



