Kenneth M. Smith 



41 



apples begin to form, the Capsids transfer their attention to these, which 

 in their turn become rapidly covered with red spots, each spot, of course, 

 marking the point of insertion of the stylets. Thus far the injury to 

 the apple appears identical with that of the leaf, but after a short time 

 the apple becomes cracked, a corky layer is formed, and a very distorted 

 fruit results; in many cases the badly attacked apple ceases to grow and 

 falls off. This is in marked contrast to the other three species mentioned 

 above which feed in a similar manner and yet produce no ill effects 

 whatever. The question then arises, what is there about this particular 

 species in contrast with the others, that the sucking action should be 

 followed by so lethal an effect upon the tissues of the foliage and fruit. 



Fig. 1. Adult specimen of Plesiocoris rugicollis. After Petherbridge and Husain. 



When this bug has sucked some of the sap, which it does by pushing 

 its sharp stylets into the tissue and drawing up the liquid by means of 

 a powerful pump situated in the head, at the same time injecting saliva 

 into the wound (Awati(4)), the stylets are withdrawn and inserted else- 

 where, meanwhile a drop of fluid gathers at the first puncture gradually 

 getting larger as the cells are killed and yield up their contents. When 

 this drop has dried up, the cells underlying it are all killed leaving a 

 large discoloured patch which may continue to spread slightly especially 

 if in the neighbourhood of a vein. 



