THE INSECT PESTS OF SHADE TREES 

 AND SHRUBS. 



By H. T. FERNALD, Massachusetts Agricultural College. 



The insects which attack our ornamental trees and shrubs are 

 of many kinds and work in a variety of ways. Almost every 

 kind of plant has its especial foes, while numerous general feeders 

 may be found on many different plants. Some feed on the roots, 

 others bore in the trunk or branches, many more consume the 

 leaves, and others suck the sap from the branches or leaves. 



Such a diversity of methods of attack renders necessary corre- 

 sponding methods for checking the ravages of these pests, and a 

 knowledge of how the insect causes the injury is in each case 

 necessary before successful treatment can be undertaken. So 

 many different insects are concerned, however, that anything 

 like a careful consideration of them must be left to special works 

 on the subject, and only general considerations and a more 

 complete discussion of a few of the most serious pests can be 

 included here. 



In general, insects feed either by biting off and swallowing 

 pieces of the plant, or by sucking its juices. Biting insects are 

 provided with jaws for this purpose, while in sucking insects the 

 mouth-parts are combined to form a sucking tube, together with 

 structures which enable these insects to make holes through the 

 surface of the plant to where the sap is, and then to suck this 

 into their bodies. 



With biting insects, a poison spread over the surface, which the 

 insect will swallow as it feeds, will pass to the stomach of the 

 pest and cause it to die, and such poisons are generally called 

 stomach poisons, for that reason. The more usual stomach 

 poisons used are paris green and arsenate of lead. For sucking 

 insects, stomach poisons spread, as they must be, on the surface 

 of the plant are of no value, the sucking tube of the insect being 

 passed through this layer into the hole it makes in the plant, 

 while the plant juices are extracted from beneath the surface. 

 For such insects as these, then, other methods of control must be 



