817 
No. 145.] 
cause of the mischief, several of the worms being present in the 
roots. This, taken in connection with the modification which the 
habits of the worm undergo when in this situation, 
is a remarkable fact. Although the plum abounds 
in gum like the peach, none of this gum exudes 
from its root when attacked by this borer. The 
worm, therefore, having no covering to protect it, 
does not erode the bark and nestle upon the out¬ 
side of the root of the plum as it does in the peach, 
but lies under the bark and subsists entirely upon 
the soft sap-wood of the root. Commencing slight¬ 
ly below the surface of the ground it works its way 
downwards immediately tinder the bark for a dis¬ 
tance of about four inches, forming a long and some¬ 
what irregular cylindrical channel. The annexed 
cut shows this burrow as it appears when the bark is removed from 
the root. As the worm moves along it packs its castings, which 
appear like a tan colored powder, into the channel behind it. 
This is an important fact, showing that if no peach trees were 
cultivated in our country this species would still sustain itself 
without difficulty in the roots of the plum. Indeed, as this insect 
is a ‘ Native American,’ wholly unknown in the peach trees of 
other countries, it is quite probable that before the peach was in¬ 
troduced upon this side of the Atlantic it bred exclusively in our 
indigenous species of plums, and has now almost entirely forsaken 
these and attached itself to this more congenial foreigner. 
The larva is a naked soft white cylindrical grub, slightly flattened on its under 
side (of which the left hand figure of the accompanying cut gives a 
view), and when full grown measures over half an inch in length 
and nearly a quarter of an inch in diameter. It is divided into 
fourteen nearly equal segments by broad shallow transverse con- 
strictions. Its head is shining yellowish red, marked in front with 
black and at base in the middle with whitish, wbioh last is also the 
color of the throat. Two impressed lines on the face converge and 
meet each other towards the base nf the head and then diverge. 
Inside of and parallel with these are two slender black lines meeting each other in 
the form of a letter V. The jaws are black and strongly notched at their tips, form¬ 
ing two sharp equal teeth. The upper lip is blackish with a pale stripe in the mid¬ 
dle. The palpi or feelers are conical and two-jointed, and inside of their base is the 
[Assembly No. 145.] 52 
