54 
the bark at any time during fall, winter, and early spring. If the 
tree has been long infested, the bark is usually perforated by small 
roughly semicircular holes about twice the diameter of the head of 
an ordinary pin. (Fig. 58.) These holes are made by the beetles 
when they come out in May and June for their brief life in the 
open air. 
The beetle (Fig. 59) is a hard, small, bronze-green or violet in- 
sect, varying somewhat in size, but approximately half an inch long 
or a little less. It is shining but minutely punctured under a glass, 
Fig. 58. Exit holes of the Bronze Birch-borer, Agrilus 
anxius, in the bark. Natural size. (Cornell Experiment 
Station.) 
Fig. 59. Bronze Birch-borer, Agrilm 
anxius, adult. About 5 times natural 
size. 
with the sides nearly parallel, tapering conspicuously behind to a 
blunt tip, notched where the rounded ends of the wing-covers come 
together. 
Altho most notorious for its injury to the white birch, es- 
pecially the cut-leaved variety, it infests all the birches. It is the 
most destructive enemy of these trees in the Chicago parks, thru 
which it is generally distributed. It is especially dangerous because 
there is no means of destroying it which does not involve also the 
destruction of the infested tree. It is a saddening conclusion which 
is forced upon the owner of a beautiful birch infested by this borer, 
that the tree is doomed, and that the only means of saving other 
trees in its neighborhood is to cut it close to the ground in winter or 
spring, as early as the first of May, and to burn it, trunk and 
branches, before the beetles can emerge to lay their eggs elsewhere. 
