The Peach-Tree Borer. 185 



The above table indicates that usually bj far the larger propor- 

 tion of the borers get less than half their growth before going into 

 hibernation in New York and northward. They are naturally 

 hungry after their long winter's fast and their strong jaws are kept 

 busy during the spring in satisfying this hunger and providing for 

 the rapid growth of their body. It is surprising how rapidly the 

 smaller borers grow in the spring. Some of the borers we dug out 

 on April 19th, 1895, were so small, only one-fourth of an inch long, 

 that we were loth to believe that they would get their growth and 

 develop into the perfect or adult insect that season. We trans- 

 planted some of these small borers onto trees in cages in the insec- 

 tary on the same day they were found, A])ril 19th. They soon got 

 to work and grew so rapidly tliat in the next ninety days, or by July 

 20th, they had not only grown into caterpillars an inch long, but 

 these had s])un cocoons, transformed to pupae, and the adult insect 

 or moth had emerged. 



This question of when the peach-tree borer does most of its dam- 

 age has a very important bearing on one of the most successful 

 methods of combating it. In the South, the borers apparently get 

 most of their growth or do most of their damage in the summer and 

 fall, as most of them pass the winter as nearly full-grown borers. 



The cocoon. — In New York, and probably in most Northern 

 States, some of the peach-tree borers attain their full growth in 

 most years by June 5th, while others do not reach this stage until a 

 month or more later ; in 1899, however, some of them must have 

 become full-grown by May 15th, for we found pupse on May 26th. 

 When full-grown the borer leaves its burrow under the bark and 

 proceeds to make around itself what is known as a cocoon. This is 

 a rough, brown, elongate-oval capsule with slightly pointed ends 

 and is about an inch in length. It is constructed by the borer of 

 its excrements and particles of bark, these being bound together 

 with gum and a thin smooth inner lining of silk. A cocoon is 

 shown natural size, where it was made by the borer, at c in figure 

 47, and two others are also shown in figure 48 ; the one in the right 

 of this figure is of unusual length. It takes the borer from two to 

 three days to complete its cocoon. 



The cocoons are usually attached to the outside of the bark of the 



