Kenneth M. Smith 53 



extract of Plesiocoris rugicollis. It seems fairly certain that a Capsid 

 that produces damage to one plant produces damage to every plant 

 upon which it feeds, although this damage varies slightly according to 

 the reaction of the plant juices to the saliva. No case was found by the 

 writer of a Capsid that was harmful to one plant being harmless to 

 another, and conversely the harmless apple bugs, when induced to feed 

 upon willow, were harmless to that also. 



Lygus pabulinus was found feeding upon many different plants and 

 trees, as shown in the following list; the effect produced in each case is 

 given. 



Bed Currant. Reddish white patches and puckerings of leaves. Fruit untouched. 



Black Currant. Whitish patches on leaves. Fruit untouched. 



Pear. Black spotting of fruit and leaves. 



Apple. Red spots and patches. 



Plum. Red spots and patches. 



Gooseberry. Reddish white patches on leaves. Fruit untouched. 



Bindweed. Clear patches of dead cells. Similar to damage to willow. 



Dock. Red spots. 



Artichoke. Whitish patches with crinkling. 



Potato. Brown spots. "Shot Hole" effect. 



Willow. Clear patches of dead cells. Compare Bindweed. 



This list would apply equally well to the effects produced by P. rugi- 

 collis. 



In all the above instances L. pabulinus was found feeding under 

 natural conditions except in the case of the apple where they were 

 "sleeved" on the tree. A number of young specimens of L. pabulinus 

 were placed on small apple trees growing near some currant bushes 

 without any measures being taken to prevent their escape ; they remained 

 upon the apple trees several days, causing a certain amount of damage, 

 and then migrated to the currant bushes. It seems probable that if 

 these specimens had been newly hatched they would have stayed upon 

 the apple trees as it is quite easy to rear them under controlled con- 

 ditions upon apple from early stages to adults. 



An American worker, C. R. Crosby (7), records two species of Capsids, 

 Heterocordylus malinus and Lygidea mendax, as living upon apples in 

 America, and describes and figures injury exactly similar to that pro- 

 duced by Plesiocoris rugicollis and Lygus pabulinus, the two species more 

 particularly dealt with in this paper. 



An interesting point arises as to why P. rugicollis should have changed 

 its food plant from willow and alder to apple, and if this species could 

 do so why should not L. pabulinus do the same? It will be seen from the 

 table of food plants that it has already a varied diet, it can also be 



