52 BULLETIN NO. 3, DIVISION OF ENTOMOLOGY. 



line. The anal segment is provided with two unequal-sized terminal 

 teetb on each side of the vent. (Plate I, Figs. 8 and 9.) 



The chrysalides vary much in size, and some of them are infested with 

 an ichneumon fly, which preys on the caterpillar. A pupa was observed 

 endeavoring to make its way to the surface of the bark, but seemingly 

 unable to extricate itself, when assistance was rendered by enlarging 

 the orifice. It was laid in a paper box for hatching. A few days after- 

 wards many minute ichneumons were observed resting upon the wall 

 near the box. On examination they were found to be escaping through 

 minute holes in the pupa, which would barely admit a No. 3 entomolog- 

 ical pin. Fifteen of these perforations were counted in this pupa. I 

 presume that the larva of the Cossus is pursued in its burrows by the 

 parent parasite. If so it is curious that the Cossus pupa is not killed 

 by the parasites until it has worked itself up to the mouth of the tun. 

 nel, thus allowing the ichneumon flies to escape outside. 



When ready to emerge, the pupa, by means of stout cusps on its ab- 

 dominal segments, works itself to the end of the opening, and with its 

 pointed head-case the thin portion of bark which has been left by the 

 caterpillar's instinct is severed and removed. It pushes itself through 

 the opening as far as the base of the abdomen, by a sort of rotary mo- 

 tion, which acts in its mode of cutting like a carpenter's center-bit. The 

 thoracic end of the pupa after exposure a short time to the air becomes 

 dry and splits, and the moth escapes, climbing up the bark of the tree, 

 shaking out its wings, until developed. After the moth has escaped the 

 empty pupa-case may still be seen protruding from the entrance of the 

 tunnel. It is not true that Cossus centerensis prefers dead wood to bur- 

 row in. It is a fact that it is most frequently found in partially decayed 

 trees, for after the larvae obtain a lodgment by its perforations in di- 

 verse directions through the heart and alburnum, admitting air and 

 water, it causes irreparable decay. There are three species of poplar 

 found in the vicinity of Centre,* viz, grandideutata, dilatola, anil tremu- 

 Joides, but as yet C. centerensis has only been found in the Populus 

 tremuloides. 



It is stated by Harris that C. ligniperda deposits her eggs on the bark 

 near the root of the tree, which I believe is the habit of most of the 

 borers. It would seem from the following that it is not the invariable 

 mode. In splitting open a tree trunk on June 12 a Cossus was observed 

 to fly from the cleft, which on being captured proved to be a female. 

 It was supposed she had taken possession of a tunnel for the purpose 

 depositing her eggs. The loose debris from the excavations was 

 gathered together, an examination of which revealed Cossus eggs, 

 (Plate I, Figs 1 and 2.) The female was confined in a box; the next 

 morning she had deposited fifty-two eggs; some of them were attached 

 to the sides and others on the bottom of the box. Some of the eggs 



*Now called Karuer. 



