590 THE BORERS OF CERTAIN SHADE TREES. 
the month of June and in the beginning of July; for, in the 
course of thirty years, I have repeatedly taken them at vari- 
ous dates, from the 5th of June to the 10th of July. It is 
evident, from the nature and extent of their depredations, 
that these insects have alarmingly hastened the decay of the 
Fig. 115. elm-trees on Boston Mall and Common, and 
. that they now threaten their entire destruc- 
| tion. Other causes, however, have prob- 
ably contributed to the same end. It will 
be remembered that these trees have greatly 
suffered, in past times, from the ravages of 
canker-worms. Moreover, the impenetrable 
state of the surface-soil, the exhausted con- 
dition of the subsoil, and the deprivation of all benefit from 
the decomposition of accumulated leaves, which, in a state 
of nature, the trees would have enjoyed, but which a regard 
for neatness has industriously removed, have doubtless had 
no small influence in diminishing the vigor of the trees, and 
. thus made them fall unresistingly a prey to 
insect-devourers. The plan of this work 
precludes a more full consideration of these 
and other topics connected with the growth 
and decay of these trees; and I can only 
add, that it may be prudent to cut down 
and burn zll that are much infested by the 
borers.” 
ee The Three-toothed Compsidea (Fig. 115), 
tridentata, is a rather flat-bodied, dark brown beetle, 
with a rusty red curved line behind the eyes, two stripes 
on the thorax, and a three-toothed stripe on the outer edge 
of each wing cover. It is about one-half an inch in length. 
The larva (Fig. 116, drawn from the living specimen) is 
white, subcylindrical, a little flattened, with the lateral fold 
of the body rather prominent; the end of the body is flat- 
tened, obtuse, and nearly as wide at the end as at the first 
abdominal ring. The head is one-half as wide as the pro- 
Compsidea tridentata, 
