June, '19] HARTZELL: PINE TUBE MOTH 235 



means of a thread spun from the silk glands. Because of their shyness, 

 minute size and protective coloration they are difficult to studv in the 

 field. 



The larvae build tubes by drawing together the leaves of the white 

 pine with silk. The leaves are placed longitudinally side by side and 

 are bound together by means of silken threads. From five to twenty 

 leaves are used in its construction. At first the tube consists of five 

 leaves, the number in a single fascicle, but as the larva grows more and 

 more are drawn in to feed upon. Usually two or three are left uneaten 

 which serve to hold the tube in place even when many of the older 

 leaves that constitute it are dead. The larvae live singly. It was 

 thought probable that the caterpillars may occupj^ more than one tube 

 during its larval life. From the beginning of the study the writer had 

 noticed that pupse were commonly found in new tubes. In order to 

 prove that a caterpillar may occupy more than one tube during its 

 larval life, a larva of the last instar was removed from its tube and 

 placed on a pine branch. In a few days the branch was examined and 

 on it was a roughly constructed tube which the larva hastily made prior 

 to pupating. 



The first larvae were observed in the field July 20, 1915. At that 

 time they were 3 mm. in length. The head measurements varied 

 from .282 mm. in the first instar to .848 mm. in the sixth instar. 



The Pupa 



The pupal skin at first is soft and pliable. The color is greenish-yel- 

 low, resembling that of the larva. In eight or ten days the skin 

 hardens and turns brown with a green tint along the wing pads and 

 thorax. Specimens examined October 20, 1915, showed structural 

 resemblances of the mature pupa except that in a number of cases the 

 antennae were more sharply defined than in the mature specimens. 



The pupae are found in October in the upper ends of the tubes, 

 enveloped in silk. The insect hibernates in the pupal state. That 

 the insect may not invariably pass the winter as a pupa was brought to 

 the writer's attention by the discovery of a live larva in a tube on 

 December 23, 1916. 



Number of Generations 



It is commonly believed that a second generation occurs in the 

 latitude of central New York. The data gathered in this study 

 indicates that the insect is singly brooded, but more research is needed 

 to establish this fact. 



