INSECTS INJURIOUS TO THE OAK. 33 
they all have this same habit of cutting off the limbs of trees, one perhaps preferring 
the wood of one kind of tree, another, another. This is the more probable, since 
there is considerable diversity in their operations, as shown by an examination of the 
fallen limbs. Thus the scarlet oak, instead of having a hole bored in the severed end 
of its limbs, commonly has half the wood ate away on one side of the limb for the 
length of an inch or more, with the cavity thus formed under the bark packed with 
worm dust, and a cylindrical burrow from the upper end of this cavity running up- 
wards in the center of the limb, the same as in other cases. 
It further appears that the female, when ready to drop an egg, is not always able 
to find a small twig with a green succulent end adapted to her wants. She then con- 
signs her progeny to the bark of the main limb, and the young worm subsists on the 
soft pulpy matter between the bark and the wood, excavating a shallow irregular 
cavity which is packed with worm dust, till it has acquired sufficient strength to 
gnaw the wood, when it cuts off the limb as in other cases. It may, however, be a 
different species from the common oak pruner, which cradles its young thus beneath 
the bark instead of in a lateral twig. It is usually in the fallen limbs of the beech, 
though scmetimes in those of the oaks also, that I have met with these worm tracks 
under the bark. 
The bark of the beech, it will be recollected, is quite thin and very brittie, so that 
it will illy serve to hold the limb in its place if the wood underneath is cut off in the 
usual manner. And accordingly a remarkable modification of this operation will be 
noticed in the amputated limbs of this tree. The worm eats its way down the limb 
beneath the bark until it has acquired sufficient strength to sever the woody fibers. 
It then passes transversely around the limb beneath the bark, girdling it by cutting 
off all the softer outer fibers and leaving the harder ones in the middle of the limb 
uncut, whereby the limb is sustained until the wind strikes it. How surprising that 
these little creatures have such intelligence given them as enables them to vary their 
operations to such an extent, according to the circumstances of their situation in each 
particular case! I should be inclined to think the beech pruner a different species 
from that of the oak, as it dwells beneath the bark instead of in a lateral twig, and 
cuts off the outer instead of the inner wood of the limb; but the worm is identical 
with that of the oak in its external appearance, and one of these worms which I 
placed in a cage, falling from its fractured burrow in the beech limb, forsook this 
wood and commenced boring into an oak limb lying beside it. 
Not only the limbs but small young trees, at least of the white oak, are sometimes 
felled by these insects; in which cases the worm, instead of cutting the wood off 
transversely, severs it in a slanting or oblique direction, as though it were aware the 
winds would prostrate a perpendicular shoot more readily by its being eut in this 
manner. 
The larva grows toa length of 0.60, and is then 0.15 thick across its neck, where it 
is broadest. It tapers slightly from its neck backwards, the hind part of its body 
being nearly cylindrical. It is asoft or fleshy grub, somewhat shining and of a white 
color, often slightly tinged with yellow, its head, which is small and retracted into 
the neck, being black in front. It is divided into twelve rings by very deep, wide, 
transverse grooves. The neck or first ring is much the largest, and shows two very 
pale tawny yellow bands on its upper side, the anterior one slightly broken asunder in its 
middle, and on each side beyond the ends of these bands is a spot of the same color 
The two or three rings next to the neck are shorter than the others, and less widely 
separated from each other. A faint stripe of a darker color may be discerned along 
the middle of the back, widely broken apart at each of the sutures. The last ring is 
much narrower and more shining than the others, and is cut across by a fine trans- 
verse line, dividing it into two parts, of which the hinder one or tip is bearded with 
small blackish hairs, and a few fine hairs are perceptible upon the other rings. The 
two last rings are retracted into the ring which precedes them, at the pleasure of the 
animal, whereby this ring becomes humped and swollen; and it appears to be chiefly 
3 RIL | 
