52 BULLETIN NO. 3, DIVISION OF ENTOMOLOGY. 
jine. The anal segment is provided with two unequal-sized terminal 
teeth 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 
amable 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 wal] 
near the box. On examination they were found to be escaping through 
minute holes in the pupa, which would barely admit a No. 5 entomolog- 
jeal 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- 
adlominal 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 
gaterpillar’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, elimbing up the bark of the tree, 
shaking out its wings, untildeveloped. After cre 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 isa fact that.it is most frequently found in partially decayed 
trees, for after the larvee 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, grandidentata, dilatola, and tremu- 
doides, but as yet C. Generar st has only been found in the Populus 
tremuloides. 
It is stated by Harris that C. ligniperda deposits her eggs on the bark 
jiear 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 trunkon June 12a Cossus was observed 
to tly 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 
o depositing her eggs. The loose débris 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 wens attached 
fo me. sides and others on the bottom of the box. Some of the eggs” 
*Now called Karner. 
