Investigation of Scarring of Fruit by Apple Redbugs 189 



^» 



Certain varieties of apples are more subject to fatal injury than are 

 others. Apples that grow to a large size, such as the Twenty Ounce 

 and pippin varieties, develop rapidly 

 and can withstand or recover from 

 wounds that cause a slow-growing 

 variety to. drop. The Northern Spy 

 is a variety that develops slowly fol- 

 lowing the set of the fruit, and thus 

 the injured fruits are more likely to 

 drop. Vitality in the development of 

 the fruit is particularly noticeable in 

 pippin and Twenty Ounce apples in- 

 jured by the larvae of the fruit-tree 

 leaf-roller. These fruits may have 

 part of the core eaten out and still 

 develop to maturity, showing the Fig. 24. mature northern spy apple 



remains of the core tissue at the SSrp"^?^/^™^"™^ ""'''" 



bottom of the wound. 



If the core of the young apple is punctured by feeding redbugs, the 



flesh of the fruit never grows back at the point of puncture and a deep 



pit results in the mature apple (figs. 23 and 24). Later, when the fruit 



is of such size that 

 the insect is unable 

 to reach the core, the 

 flesh will develop be- 

 neath the point of 

 puncture and tend to 

 reduce the depth of 

 the pit. When the 

 growth is sufficiently 

 rapid the pit may dis- 

 appear entirely and a 

 spreading russet, scar 

 take its place. After 

 the apples have 

 reached more than a 

 quarter of an inch in 



Fig. 25. YOUNG northern spy apples (july 8) showing diameter, growth is 



THE splitting AND SPREADING SCARS THAT DEVELOP FROM , • j -i .1 



PUNCTURES MADE BY REDBUGS vcry rapiQ, anQ tne 



punctures made by 

 the redbugs cause a splitting of the fruit skin which continues to enlarge 

 with the growth of the apple until broad russet scars result (figs. 25 



299 



