8 FARMERS’ BULLETIN 675. 
inch or more beneath the bark. As previously stated, part of the 
borers do not become adult until they are 3 years old; these re- 
main feeding in the wood near the ground until the third summer, 
when they, too, work their way up the trunk in the manner just de- 
scribed. The winter previous to pupation is passed by the borers 
in the pupal cell or chamber (fig. 12). This chamber is a space at 
the upper end of the gallery which curves out to the inner bark above 
and contains in the curved portion next to the bark a small quantity 
of fine, sawdust-like particles of wood. The chamber is 2 or 3 inches 
in length, being limited 
at the lower end by a 
packing of coarse, string- 
like wood fiber. In the 
spring the point at which 
the chamber extends to 
the inner. bark begins to 
show from the outside as 
a slightly depressed, 
dead spot in the bark. 
This spot marks the 
place from which the 
adult is to issue later, 
and is especially notice- 
able on young, smooth- 
barked trees. 
THE PUPA. 
The pupa (fig. 13) is 
an intermediate form be- 
tween the larva, or borer, 
Fic. 8.—Female beetle placing an egg in the tree and the beetle which de- 
below the-surface of the ground. (Original.) 
posits the eggs. In this 
form the insect is of about the same color as the borer, but the 
shape is greatly changed, the legs, wings, antenne, and other 
appendages which the adult is to possess being now visible. The 
insect does not feed while in this stage and is incapable of mo- 
tion except that of wriggling about in the chamber. It occupies 
a vertical position in the tree with its head up. The change 
from the borer to the pupa takes place at the time apple trees 
are in bloom, the pupal stage covering a period of about three 
weeks. 
