74 DECIDUOUS FRUIT INSECTS AND INSECTICIDES. 
FEEDING HABITS WITHIN THE BURROW. 
There is no regular method of forming a burrow. After the borers 
have penetrated into the cambium layers, they may move upward 
or downward or to the side. The burrow may be long and narrow 
or short and broadened. The larva moves about in its burrow at 
will and cleans out the frass and exuding gum and ejects it through 
the outer opening and because of this the opening often becomes a 
more or less conspicuous tube of such castings. The castings and 
exuding gum are quite conspicuous and always indicate the presence 
of worms and show where the burrows are. Where many worms 
completely girdle a tree there are no individual burrows, and the 
worms may then be feeding closely together. 
THE PUPA. 
(Fig. 22, b, c.) 
FORMATION, STRUCTURE, AND POSITION OF COCOON. 
The mature larva selects a place to form its cocoon near some kind 
of an opening where the adult moth can readily escape. This may 
be near the entrance to the burrow, or near a break in the bark, or 
if under unbroken bark the worm may eat out a small round exit 
hole before it goes into the cocoon. Larvee which are located in the 
larger roots pupate in the usual way if these roots are near the sur-. 
face. On May 26, 1908, during the process of worming 6 pups were 
dug out from a root and in this case they were 12 to 15 inches away 
from the trunk of the tree. Larve often move out from the lower 
roots and also occasionally leave the tree trunk and pupate a few 
inches below the surface and in the open soil several inches away. 
On one occasion 7 empty cocoons were found from 1 to 5 inches away 
from the tree and from 1 to 3 or 4 inches below the surface. Occa- 
sionally pupz may be found 2 feet or more above the ground in the 
lower branches. On June 10, 1907, 2 pupz were found in the sun- 
burned area on a large branch, several feet above the ground. 
The cocoon is constructed of chewed particles of bark and wood, 
excreta, and gum, and bound together by a silken web and lined’ 
inside with silk. The completed cocoon is exceedingly tough and 
strong and rather rigid. The anterior end alone is thin and weak 
and offers only a little resistance when the mature pupa begins to 
force its way out. Cocoons which are located in the soil are made 
of particles of earth, but they, like others, are held together and 
lined with silken threads. The cocoon is elongate oval in shape and 
about an inch in length. Female cocoons are larger than those 
of males, although they, too, are sometimes abnormally small when 
