160 



ORDER HEMIPTERA 



limit. It can be controlled by spraying with kerosene emul- 

 sion during the larval stage. 



The subdivision Parasita includes the suctorial lice, and 

 they present perhaps the greatest divergence from the 

 normal form, the extreme being in the direction of reduction 

 due to parasitism. They are entirely wingless; they have 

 a reduction of the mouth parts which is extreme. The beak 



Fig. 116, — Stink bug: a, adult; b, eggs attached to leaves; c, d, e, f, 

 details of egg structure. (Bur. Ent. U. S. Dept. Ag.) 



is reduced to a single segment through which the tubular 

 setse are projected — a derivation from the three- or four- 

 jointed beak of the normal forms. There is a distinct 

 reduction or retrogression in the wings and mouth parts, 

 but a distinct specialization in the structures by which 

 they clasp the hairs or feathers of host forms. Tarsal claws 

 are very large and strong and are provided with ridges or 

 roughened areas which seem to strengthen the hold upon 



