SB 
818 
C57 
ENT 
8 
No. 24, SECOND SERIES. 
United States Department of Agriculture, 
DIVISION OF ENTOMOLOGY. 
THE TWO-LINED CHESTNUT BORER. 
(Agrilus bilineatus Weber. ) 
RECENT DAMAGE TO FOREST GROWTH. 
Recent years have witnessed extensive destruction of forest growth, 
particularly of pine, spruce, and chestnut, in portions of the United 
States east of the Rocky Mountains. This injury has been very 
generally attributed to insects, and there is evidence that certain 
wood and bark-boring species have largely contributed to the work 
of demolition. The death of the chestnut trees was laid to the 
account of the little buprestid borer, Agrilus bilineatus, which 
forms the subject of this circular, and the destruction of the conifer- 
ous trees was, in like manner, accredited to the scolytid bark-beetle, 
Dendroctonus frontalis Linn. 
A peculiar and interesting feature of what may be called primary 
insect injury is that it was due very largely to native species not pre- 
viously known to be injurious. Another singular fact is that the 
invading forces disappeared as suddenly as they came, and, as is 
usual in such cases, we are as ignorant of the reason for the insects’ 
disappearance as we are of the inducing cause. As usual also in so 
many similar instances, these cases of forest-tree injuries were not 
brought to the attention of entomologists until too late for thorough 
investigation or experiment. 
Since the year 1893 the pine-infesting species has not been reported 
as injurious, and, in fact, it seems to have entirely disappeared. The 
opinion has been expressed that its disappearance was due to a fungus 
disease, and it is possible that such is the case. The chestnut-boring 
species, however, is still living throughout its accustomed range and 
in normal abundance. 
PROBABILITY OF FUTURE DESTRUCTION OF TREES. 
The severe wind storms that swept over the South Atlantic States 
during the year 1896, particularly that of September 29, which was 
the severest ever known in this region and caused very extensive 
destruction of forest and shade trees, will doubtless result in still 
