190 



FRUIT INSECTS 



the grub or borer sheds its skin in this specially prepared chamber 

 and appears in the pupal stage, a delicate, yellowish-white ob- 

 ject, somewhat resembling the adult insect (Fig. 183). This 

 ^^^^^ pupa gradually grows 



|^|H^^^^ darker in color and in 



BRhhHK^' about three weeks trans- 



W- '''''01- * forms to the beautiful 



adult or beetle which 

 soon emerges from a 

 round hole (Fig. 184) 

 al^out the size of a lead 

 pencil cut through the 

 bark with its strong, 

 sharp mandibles. 



As it spends most of 

 the three years of its 

 life inside the tree, this 

 apple-borer has few nat- 

 ural enemies. Wood- 

 peckers get some of the 

 grubs, and at least one 

 hymenopterous parasite, Cenocoelius populator, sometimes helps 

 to reduce their numbers. 



Preventive and remedial yneasiires. 



Borers are among the most difficult to control of all insects 

 attacking fruit-trees. No thoroughly satisfactory method of 

 preventing the ravages of this round-headed apple-borer has 

 yet been found. The owner of the quince orchard mentioned 

 in the first paragraph of the discussion of this borer thoroughly 

 tested the commonly recommended preventive washes and 

 shields besides constantly practicing the '' digging-out method." 

 Yet so severe was the infestation that all measures failed and 

 the orchard was ruined, the owner giving up the fight and 

 destroying the trees. The statement often made that paper 



Fig. 184. 



Exit hole of the round-headed 

 apple-tree borer. 



