82 NEW YORK STATE MUSEUM 



soft inner bark, later penetrating the liarder sapwood and finally resorts to 

 the solid heartwood, residing mostly in and around the center of the trunk, 

 boring the wood in a longitudinal direction, and moving backward and 

 forward in its burrows enlarging them as it increases in size. The entire 

 excavation is therefore of a nearly uniform diameter. Dr Fitch records 

 meeting fully grown and others but half grown in one tree, and adds that 

 the same oak had been extensively mined by preceding generations of this 

 insect, and was decayed. The writer has met with at least two very different 

 sizes of larvae in one tree at the same time. Dr Fitch records the fact 

 that none of the caterpillars were in decaying wood, but all were working in 

 tissues which were still sound, and adds that the insect evidently prefers the 

 healthy tree. Mr L. H. Joutel recently found two young larvae of this 

 species feeding on the pupae of Cyllene robiniae Forst. and another 

 about to devour a pupa, indicating a willingness on the part of these cater- 

 pillars to vary their diet. The life cycle of this species is believed to 

 occupy three years, and certainly extends over two at the very least. The 

 transformation to the pupal state occurs in oval cells made at the extremity 

 of the galleries. The free end of the burrow is packed with borings [pi. 5, 

 fig. 6]. The appearance of the adult is preceded by the pupa working 

 itself along the gallery and partly out of the entrance to the burrows [pi. 5, 

 fig. 5]. This permits the disclosure of the moth in the open air, and 

 thus avoids her being injured by crawling through rough and devious gal- 

 leries. The duration of the pupal stage has been given by Dr Fitch as 

 probably two weeks or longer. See plate 30 for this borer's work. 



Description. The adult insect is a magnificent, grayish moth having a 

 wing spread in the female of about 3 inches. Her general color is a 

 dark gray mottled with a very light gray, and with traces of yellowish on 

 the hind wings. The males are considerably smaller, with a wing spread 

 of about 2 inches, and they may be quickly recognized by the large orange 

 red marking on the hind wing. The male is darker than the female, the 

 forewings being a very dark gray with a few light gray mottlings. The 

 anterior portion of the hind wings is nearly black, and there is a large 



