69 



The injury to chestnut was almost universal, the majority of the 

 infested trees having been recently killed — within a year or two — few 

 having been dead more than two or three years. The origin of the 

 trouble may thus be traced back to about the year 1890 or 1891. or pos- 

 sibly a year or two earlier. 



The estimated damage was placed by Mr. Wedderburn at about To 

 per cent for this vicinity, and he further stated that a similar condition 

 of affairs existed at this time in neighboring forests of the surrounding 

 region. This was subsequently verified by the writer in conversation 

 with other landholders of this and adjoining counties. 



Two chestnut trees that had been attacked but were still living were 

 felled, the bark stripped off', and the galleries of Agrilus bilineatus 

 exposed. These galleries run mainly transversely just under the bark 

 and are in length from 6 to 10 inches. Although none were found that 

 completely encircled the tree, the result is practically that of girdling, 

 through the combined work of many different individuals. 



From the manner of the insect's work it can not be otherwise than 

 exceedingly injurious, as it undoubtedly stops the flow of sap, cuts off 

 the natural supply of plant food and moisture, and greatly Aveakens and 

 eventually kills the tree. The galleries occur from the base of the 

 trees well up toward the top. 



The Agrilus was rather common on the foliage of both chestnut and 

 oak, and a few larvae and adults that had not yet issued were found 

 under the bark of dead trees, but in the living trees the insects had 

 evidently long before left the wood and had either issued or were still 

 in the bark, as none were to be found after long search. Their charac- 

 teristic galleries and exit holes, however, were noticed in all of the 

 dead and (lying chestnuts examined. From the observed fact that no 

 other insect was present in any number in the infested trees that were 

 still living there can be little doubt that the damage to the chestnuts 

 is caused chiefly by Agrilus bilineatus, although, as stated in a pre- 

 vious paragraph, it is more than probable, judging from what is known 

 of this and other similar bark-boring beetles, that the trees are first 

 enfeebled from some other cause. A reason that may be adduced for 

 this belief is that this buprestid is better known as an enemy <»t" the 

 oak, yet the trees of this genus did not show any evidence o( attack. 

 while the chestnuts were evidently all infested. Chestnut trees were 

 also dying in the District, and it seems probable that tin's trouble is 

 widespread. It is obvious that only the earlier stage of the larva 18 

 passed between the bark and the wood; indeed, it is likely that the 

 entire life of the insect maybe passed, in some instances at hast. 

 entirely within the bark. 



The pupal chamber is evidently always constructed in the bark of 

 living trees, but was also found in the wood just under the bark of 

 small dead trees. In larger trees the last portion of the larval gallery 

 is longitudinal and carried up to within a short distance of the outer 



