ROUNDHEADED APPLE-TREE BORER. 39 



destruction of beetles of this species. Such sprays should be applied 

 about 10 days after the blossoms have disappeared from apple trees 

 and should consist of 4 or 5 pounds of lead arsenate paste to 50 gal- 

 lons of water, or of the equivalent of this strength prepared with 

 some other insecticidal poison. When trees reach a bearing age, 

 the so-called first codling-moth spray will serve also to kill the beetles 

 of the roundheaded apple-tree borer. 



SUMMARY. 



The roundheaded apple-tree borer is a native American insect 

 that has been recognized as a serious pest of the apple, pear, and 

 quince since the early days of orcharding in this country. 



It occurs in the United States and Canada over most of the apple- 

 growing region east of the Rocky Mountains. 



In addition to the cultivated fruits named above, it breeds also in 

 such wild trees as wild crab, hawthorn, mountain ash, and service. 

 These native trees growing in woods or neglected fields often serve 

 as centers in which the adults develop and from which they fly to 

 near-by orchards to deposit their eggs. 



In the woods and in orchards the insect is inclined to colonize, 

 families or communities living in the trees of somewhat restricted 

 localities. Often infestation in an orchard or in native woods will be 

 confined for years to rather definite areas or spots. This habit is due 

 largely to the inclination of the adult female to deposit her eggs near 

 the place where she developed. 



The common belief that borers of this species prefer to attack 

 trees planted in new ground, in hilly situations, or in certain kinds 

 of soils probably arises from the fact that such situations favor a 

 more abundant growth of the native host trees of the insect. In 

 these wild trees many adults develop and cause serious infestation 

 of adjacent orchards. 



About 95 per cent of the eggs from which the borers hatch are 

 deposited in the bark within a few inches of the ground. The incu- 

 bation period is about 16 days. The borers feed in the bark and wood 

 for from one to four years and finally pupate at the end of an ascend- 

 ing gallery which extends up the trunk from a few inches to approxi- 

 mately 2 feet above the ground. 



The burrows made in the bark and wood are broad and irregular 

 in form. Often several borers work close together, as many as 25 

 or 30 having been found in a single tree. Infested trees become 

 sickly in appearance. They are inclined to bloom freely and set 

 heavy crops of fruit, but often die in an attempt to bring the crop to 

 maturity. Young trees suffer most but trees of all ages are attacked. 

 Trees of an orchard standing near woods are more likely to be in- 

 jured by borers than those more distant from the woods. 



