STREPSIPTERA 



299 



other Insects, of the Orders Hymenoptera and Hemiptera. Their 

 structure and their life-histories entitle them to be ranked as 

 the most abnormal of all Insects, and entomologists are not 

 agreed as to whether they are aberrant Coleoptera or a distinct 

 Order. The newly-hatched larva is a minute triungulin (Fig. 

 154), somewhat like that of Meloe; it fixes itself to the skin 

 of the larva of a Hymenopterous Insect, penetrates into the 

 interior, and there undergoes its metamorphoses, the male emerg- 

 ing to enjoy a brief period of an abnormally active, indeed agitated, 

 existence, while the female never moves. It is important to 

 note that these Strepsiptera do not, like most other internal 

 parasites, produce the death of their hosts ; these complete their 

 metamorphosis, and the development of the parasite goes on 

 simultaneously with that of the host, so that the imago of the 



FIG. 153. Sexes of Strep- 

 siptera. A, Male of 

 Stylops dalii (after Cur- 

 tis) ; B, female of Xenos 

 rossii (after von Siebold). 



B 



A 



Strepsipteron is found only in the imago of the host. 1 After 

 the young Stylops has entered its host it feeds for a week or so 

 on the fat-body (apparently by a process of suction), then 

 moults and assumes the condition of a footless maggot, in which 

 state it remains till growth is completed. At the latter part of 

 this period the history diverges according to sex ; the female 

 undergoes only a slight metamorphic development of certain 

 parts, accompanied apparently by actual degradation of other 

 parts ; while the male goes on to pupation, as is normal in Insects. 

 (We may remark that the great features of the development of 

 the sexes are parallel with those of Coccidae in Hemiptera.) 

 AVhen the Hymenopterous larva changes to a pupa, the larva 

 of the Strepsipteron pushes one extremity of its body between two 

 of the abdominal rings of its host, so that this extremity becomes 

 external, and in this position it completes its metamorphosis, the 



1 This remark applies to the Strepsiptera parasitic on Hymenoptera : nothing 

 whatever is known as to the life-histories of the species that attack Hemiptera. 



