STATE AGRICULTURAL SOCIETY. 
7 87 
OAK. TRUNK. 
dirty whitish color with one of the ends black. When highly magnified 
their surface is seen to he reticulated or occupied by numerous slightly 
impressed dots arranged in rows like the meshes in a net. From the fact 
that several worms of the same size are sometimes met with in a single 
tree, indicating them all to be the progeny of one parent, it appears that 
the female drops a number of eggs upon each tree that she visits, and 
probably disposes'of her whole supply upon a very few trees. The size of 
the eggs doubtless renders them a favorite article of food to some of our 
smaller birds. And a bird on discovering one of these eggs, will be 
incited thereby to search for others in the same vicinity, which search being 
successful, will be perseveringly continued so long as an egg can be found 
upon that or any of the adjacent trees. Thus it may be that of the whole 
stock of eggs which a female deposits, scarcely one escapes being picked 
up and devoured. This appears the most probable cause of so few of these 
worms being met with, although the females arc so prolific. 
The worm on hatching from the egg sinks itself inward and feeds at first 
on the soft inner bark, till its jaws acquiring more strength, it penetrates 
to the harder sap-wood and finally resorts to the solid heart-wood, residing 
mostly in and around the centre of the trunk, boring the wood here usually 
in a longitudinal direction, and moving backwards and forth in its burrow, 
enlarging it by gnawing its walls as it increases in size, whereby the exca¬ 
vation comes to present nearly the same diameter through its whole length. 
In an oak in which I met with two worms fully grown and several others 
but half grown, the whole of the central part of the trunk had been exten¬ 
sively mined by preceding generations of this insect and was^n a state of 
incipient decay. And I thus had an opportunity to notice the fact that 
none of the worms were lying in the decaying wood, all being outside of 
this, where the wood was still sound. Hence it is evident that it is living 
healthy trees which this insect prefers, and not those which arc sickly and 
decaying ; which latter are preferred by the European Cossus, some authors 
say, though perhaps their observations have not been exact upon this point; 
for in the instance here alluded to, it would have been said on a first glance 
that these worms preferred decaying wood, since the diseased heart of the 
tree was everywhere traversed with their burrows, and the sound wood 
showed few of , them. And thus no doubt in many other cases we mistake 
the cause for the effect, and on seeing semi-putrid wood filled with worm- 
holes we suppose the worms have preferred wood of this character when in 
truth it is these holes which have caused the decay of the wood. 
These worms are probably three years in obtaining their growth. They 
cast off their skin several times, and after the last of these moultings their 
color becomes different from what it has previously been. 
The larva previous to tho last change of its sliin is of a rose red or apale cherry red color, 
often with a faint yellowish stripe along tho middle of its baok, on all except tho threo anto- 
rior rings. It is of a cylindrical form, slightly broadest anteriorly and a little flattened bo- 
ncath. It is divided by transverso constrictions resembling broad shallow grooves, into twelvo 
