THE SAPEKDA 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 during 

 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 mil consideration 

 of these and other topics connected with the growth and 

 decay of these trees ; and I can only add, that it may bo 

 prudent to cut down and burn all that are much infested 

 by the borers. 



The tall blackberry, Rubus 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 



