THE CANADIAN ENTOMOLOGIST. o 



to extricate itself, when assistance was rendered by enlarging the orifice. 

 It was laid in a paper box for hatching ; a few days afterwards 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 Entomological 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 tunnel, thus allowing the ichneumon 

 flies to escape outside. 



October 14th, we visited the trees which were known to be inhabited 

 by the Cossus, for the purpose of obtaining caterpillars in the different 

 stages of growth. A section of a tree measuring nearly four feet in length 

 was taken, and from it six caterpillars were secured, two of which were 

 occupying pupal cells preparatory to transformation. Judging from the 

 difference in the development of the caterpillars taken at this time, it 

 would seem as if it would require at least two years for their maturity. 



While thus far the Center locality has proved to be the chief home of this 

 Cossus, it will undoubtedly be found elsewhere wherever the Populus 

 tremuloides is found. Several pupa cases of this species have been found 

 in the corporate limits of Albany. Usually trees of less than one foot in 

 diameter are attacked, although in one instance a pupa case was found in 

 a tree measuring sixteen inches in diameter. 



The larva ; taken October 14th from its burrows, is 45 mil. in length, 

 of a pale flesh color. It is a little broader anteriorly. The prothoracic 

 segment is blackish brown above, the dark color edged with a dirty orange 

 shading. The head is mahogany brown, shining, slightly roughened. The 

 mandibles are black, with three strong teeth. The surface of the head 

 gives rise here and there to single scattered hairs. The antennae are 

 three-jointed ; the second joint gives rise to a single long hair. The 

 7 th, 8th, 9th and 10th abdominal segments are provided with false feet. 

 The segments are marked with a lateral row of brown dots above the 

 reddish stigmata, and there is a row of similar dots, two to a segment, on 

 each side of the dorsal line. These dots give rise to single pale hairs. 

 The larva moves with freedom either backward or forward. The -burrows 

 which it excavates are about 15 millimetres in width, and terminate in the 

 pupating cell, which is about 40 mil. in length, smooth ; the extremity 

 towards the opening is closed by a wad of finer and then coarser filings 



