Kenneth M. Smith 



43 



the injury did not spread and the leaves were not put back in their 

 development. 



If it is assumed that the injury is due to the mechanical laceration 

 of the cells and their consequent loss of sap by the stylets of the bug, 

 then the question arises, why do not the other species of apple feeding 

 bugs produce the same effect? as the methods of feeding, and the man- 

 dibles and maxillary stylets are precisely the same in each case. 



Fig. 2. Semi -diagrammatic drawing of the head of Lygus pabulinua showing mouth parts. 



Attempts were made under the binocular microscope to pierce the 

 leaf with the mouth-parts of various species after they had been removed 

 from the head so that there was no possibility of any salivary juices 

 being injected: this was not very satisfactory owing to the extreme 

 fineness of the stylets, but in a few instances perforation was effected 

 but with no visible results, the stylets apparently being too minute to 

 kill more than one or two cells by laceration. As regards the possibility 

 of the loss of sap by sucking causing the damage, if this were so it would 

 of necessity follow that all the species of Capsids and indeed any sucking 

 insect should produce similar harmful results. 



