78 VERMONT AGRICULTURAL REPORT. 



APPLE TREE BORERS. 



By Wiuiam Stuart, 

 Horticulturist Vermont Experiment Station. 



Borers are serious pests throughout the apple farming sections. An 

 unusual opportunity having arisen for observations upon the round- 

 headed type, the writer deems it worth while to make some brief state- 

 ments as to their nature and the means of combating them, even though, 

 strictly speaking, it lies outside of the particular province of his line of 

 work. 



The injurious effects of the round-headed apple tree borer were very 

 apparent in the orchards examined. In one, which consisted entirely of 

 trees under ten years of age, a larger per cent, of them were seriously 

 injured and many killed outright. Others were so nearly dead that after 

 blooming they failed to put forth leaves. Any tree in which a borer 

 passes its larval life is much the worse for it; and, when, as sometimes 

 happens, eight or ten make a tree their abiding place, its usefulness is 

 past. 



UFE HISTORY. 



The eggs are laid in slits in the green bark of the trunk of the tree, at 

 or near the surface of the ground. They may be deposited as high as 

 18 inches, but usually are found near the base. They are probably de- 

 posited in this latitude from the middle of June to the latter part of 

 August. The egg soon hatches and the young larva begins at once to 

 gnaw its way through the inner bark and cambium layer. On the ap- 

 proach of winter it tunnels its way down the trunk of the tree below the 

 surface of the ground. With the advent of spring it ascends and passes 

 the summer in the sap wood. The second winter is passed in a similar 

 manner to that of the first. The third season the larva again ascends 

 and bores or gnows its way into the heart wood of the tree, and in all 

 directions. Towards the close of the season it gnaws its way upward 

 and outward to the bark of the tree, after which it withdraws into its 

 burrow, encases itself with the castings of wood and soon enters into the 

 pupal stage of its existence. Early in the next June it cuts its way out, 

 emerges as a mature beetle, the female deposits its eggs and the life 

 cycle is completed. 



PREVENTIVE MEASURES. 



The sundry measures recommended looking towards prevention are 

 of two classes. They looked either to the exclusion or the repulsion of 

 the insect. It is either shut away or turned away from the tree trunk. 



