CHAPTER XX 



THE STREPSIPTERA 



These tiny insects are seldom seen except by entomologists, and 

 their parasitic habits aid in their concealment. For a long time opinions 

 were divided as to where they belonged, some regarding them as a 

 family of aberrant Coleoptera, while others considered them as forming 

 an order. Recent studies seem to confirm the latter view and the 

 group is now generally rated as a separate order, though its closest 

 relations are probably with the beetles. 



The Strepsiptera, from the meaning of this name, may be called the 

 Twisted-wing Parasites, though the words stylops and stylopid are fre- 

 quently used in referring to them. The males on reaching the adult 

 condition (Fig. 146), become free and can fly. The females on the other 



FIG. 146. Male Strepsipteron (Xenos vesparum Rossi), rather more than six times natural 



size. (After Pierce.} 



hand, remain partly within the bodies of their host insects and are worm- 

 like or grub-like (Fig. 147) in appearance. The males are very small, 

 soft-bodied animals, ranging from about one to perhaps four twenty- 

 fifths of an inch in length. The eyes are more or less stalked and the 

 antennae have one or more segments elongated on one side. The mouth 

 parts are greatly modified but appear to be of the chewing type, though 

 the adult does not feed. On the mesothorax is a pair of tiny clubs, some- 

 times rather flattened, which represent the front pair of wings. The 

 metathorax forms nearly half the entire length of the body. It bears a 

 pair of well developed wings which are broad and fold lengthwise when at 

 rest. The abdomen is composed of ten segments. The females are 

 soft and resemble a rather long sack bearing traces of segmentation, and 

 at one end a constriction, beyond which is a sort of knob, believed to be a 



150 



