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. Larvae 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 pupae were 

 dug out from a root and in this case they were 12 to 15 inches away 

 from the trunk of the tree. Larvae 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 pupae may be found 2 feet or more above the ground in the 

 lower branches. On June 10, 1907, 2 pupae 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 



