8 
will show a blackening of the bark where it has been undermined 
and always minute round punctures half or two thirds th( 
diameter of the head of a common pin. Upon the twigs thes< 
punctures are most abundant at the old leaf scars or on thi 
thick lateral sours, but they may occur elsewhere, and in th< 
thicker bark of the trunk and branches seem quite irregularly 
distributed. If the bark is cut away, these openings are seen t< 
penetrate it, commonly, to the wood, the channels usually run 
ning vertically inward, (sometimes a little obliquely); and if th 
tree be badly infested the under surface of the bark will b 
almost completely eaten out and marked by a net-work of fim 
channels of about the same diameter as the small holes already 
mentioned. The greater part of these grooves run lengthwise o 
the stem, and, except where the bark is thickest, similarly fur 
row the surface of the wood, so that when the tree is denude( 
of bark the whole surface beneath is seen to be closely engravec 
as by a minute gouge. More critical examination will sho^ 
here and there a broader burrow, running commonly lengthwise 
of the stem, nearly straight, or sometimes a little curved, am 
from this central, larger channel a great number of much smalle 
ones will pass out to the right and left as closely as they cai 
be placed, increasing in size as they go, and presently changing 
direction, so that those at first running crosswise of the sten 
become longitudinal. If one of the grooves on the surface o 
the wood be traced to its further end, one will frequently find- 
especially in the winter—a, speck of wood dust which, whei 
picked away, is seen to have closed the opening to a littli 
chamber within which the footless white grub—the larva of th< 
beetle—is securely lodged. 
This description will be better understood after the method is 
explained by which these burrows are made. The female beetle 
resorting to the tree, burrows into the bark directly inward 
and then, turning lengthwise of the branch, digs a channel fron 
half an inch to an inch and a quarter long,—the larger burror 
described above, called the breeding chamber,—laying eggs tc 
the right and left as she makes her way. As these eggs hatch 
the young larvae, very small at first, eat outward in all direc 
tions, forming the closely-placed radiating channels already de 
scribed, enlarging the burrow of course as they increase in siz< 
themselves; and finally when they have reached their growth 
each sinks itself in the sap wood to a. depth scarcely greatei 
than its own thickness, stopping the channel behind it with g 
little mass of wood fiber, and there it changes to the pupa 
stage. This terminal cell is consequently called the pupal chain 
her. In this little harborage the adult beetle appears and eat* 
its way out through an opening similar to that by which tin 
mother entered in the beginning. 
It will be seen that not all the perforations (with which tin 
bark may be as thickly peppered as if filled with a charge o 
fine shot) lead into the larger breeding chambers, but most o J 
