INSECT ENEMIES OF PRINCIPAL CROPS 167 



"set" more fruit than it can possibly mature, and corrects 

 this by a "June drop," during which most of the weaker 

 and the injured apples fall to the ground. During the rapid 

 growth that follows the drop, all wounds in apples that 

 remain on the tree tend to heal over quickly. A new skin is 

 formed beneath the old dead tissue, and scabs off more or 

 less completely, leaving a russet surface.* The scars will 

 tell us what insects caused them if we will study their form 

 and appearance carefully, f 



There are perhaps a dozen kinds of apple insects whose 

 work may often be identified in the fruit of a single tree. 

 These are shown diagrammatically in the accompanying 

 figures, and brief notes concerning them are set down in the 

 following 12 paragraphs. 



1. The apple red bug: Sucking insect; half grown when 

 the apples bloom; punctures the apple with its beak; punc- 

 tures made in very small apples reach the core and make 

 shallow irregular russet scars; scars often confluent, forming 

 "valleys" over the surface of the apple. 



2. The rosy apple aphid: A sucking insect; gregarious, 

 feeding in flocks on the new shoots; increases rapidly and 

 spreads over leaves and young fruit; punctures cause the 



* This new skin being thinner than the old sometimes yields to internal 

 pressure, rising up on wart-like protuberances. These warts have no sig- 

 nificance for us here. 



t The scars vary with the size of the apple when injured, with the 

 number and position of the wounds" made, and with the growth-habits of 

 the variety of the apple, but still they have constant features by which 

 the work of each kind of insect can be known. 



