THE SAPERDA TRIDENTATA. 
113 
wood itself; but their operations were mostly. confined to the 
inner layers of the bark, which thereby became loosened from 
the wood beneath. The grubs rarely exceed three quarters 
of an inch in length. They have no feet, and they resemble 
the larvae of other species of Saperda , except in being rather 
more flattened. They appear to complete their transforma- 
tions in the third year of their existence. 
The beetles probably leave their holes in the bark durino- 
the month of June and in the beginning of July; for, in the 
course of thirty years, I have repeatedly taken them at 
various dates, from the 5th of June to the 10th of July. 
It is evident, from the nature and extent of their depreda- 
tions, that these insects have alarmingly hastened the decay 
of the elm-trees on Boston Mall and Common, and that they 
now threaten their entire destruction. Other causes, how- 
ever, have probably 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 condition 
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 all that are much infested 
by the borers. 
The tall blackberry, Hubus villosus, is sometimes cultivated 
among us for the sake of its fruit, which richly repays the 
care thus bestowed upon it. It does not seem to be known 
that this plant and its near relation, the raspberry, suffer 
from borers that live in the pith of the stems. These borers 
differ somewhat from the preceding, being cylindrical in the 
15 • 
