THE STREPSIPTERA 



151 



combination of the head and thorax; a cephalothorax in fact. This 

 portion of the body is pushed out between two of the body segments of 

 the host during the latter part of the metamorphosis, thus becoming 

 external (Fig. 147) and the body of the host is distorted in this way. 

 The members of this order may be characterized as follows: 

 Tiny insects which from the first larval instar to the adult, are internal 

 parasites in other insects. The male adult has stalked eyes, mouth parts of 

 the chewing type, but little or not at all developed; antennce with one or more 

 segments prolonged laterally; pro- and mesothorax small, the latter with a 

 pair of small clubs corresponding to the fore wings of most insects; meta- 

 thorax long, forming at least half the length of the body and bearing a pair of 



FIG. 147. Female Strepsipteron, top and side views and a Stylopized Wasp: a, end 

 of the parasite projecting between the abdominal segments of the Wasp. All greatly 

 enlarged. (After LeuckarVs Wandtafeln.) 



broad wings which fold longitudinally. The female adult is worm-like, 

 without feet, and located within the body of its host except for a cephalothorax 

 which protrudes between two abdominal plates of the latter. It is enclosed 

 by its pupa skin. Metamorphosis complete. 



These insects, often called "stylops," are parasitic only in some 

 Orthoptera, Homoptera, Hemiptera and Hymenoptera, as far as known, 

 and at the present time only Gryllotalpa in the Orthoptera and Chryso- 

 coris in the Hemiptera are known as hosts in those groups. Most of the 

 parasitism is of leaf-hoppers, wasps and the solitary bees, and these 

 are so disabled by the removal of their body fluids by the parasites that 

 ' ' stylopized" individuals are unable to reproduce and are greatly lacking 

 in vitality. Their bodies are often distorted also and other changes are 

 produced. 



