162 THE CANADIAN ENTOMOLOGIST. 



of the caterpillars which I had fed up from the third and last moults 

 developing into these parasites — gave me the opportunity of examining 

 the mechanical skill of these insects and of noting some peculiarities of 

 habit. From the cocoon of T. Polyphevais I have obtained O. Macru- 

 rum Linn. This parasite forms a very tough oval-shaped cocoon, occu- 

 pying the larger portion of the cocoon of the moth. It is comiX)sed of 

 very fine silk agglutinated by a dark secretion. The exterior is of a dark 

 brown color, Avith a faint yellowish or golden band around the centre ; the 

 interior is lined with a thin transparent substance, possessing a brilliant 

 metallic polish. Distinguished Entomologists have asserted that this 

 parasite commonly deposits from eight to ten eggs on the Polyphemus 

 caterpillar. I cannot reconcile this statement with the observations that I 

 have made. Out of three cocoons of the Polypheinus caterpillar, I have 

 in each case obtained but one of the parasite ; indeed there is not suffi- 

 cient space within the cocoon of the moth for more than two cocoons of 

 the parasite. It is possible that some of the parasitic larvae may escape 

 from the cocoon of the moth, and undergo transformation without, yet in 

 such cases as came under my observation no such evidence existed. From 

 the chrysalid of P. Troiliis I have obtained T. Exesorius Brulle', which 

 transforms without other covering to serve as a cocoon beyond that sup- 

 plied by the chrysalid. I note that the point of exit of this parasite from 

 the chrysalid was the same in every case, viz., on the right or left side, 

 about midway of the thorax, at the widest part. From a cocoon of P. 

 Cecropia I am furnished with eight cocoons of B. Flavator Fabr. They 

 are three quarters of an inch long, and very narrow. The outer covering 

 is of loose silk ; within it is rendered more dense, the threads being drawn 

 together by a gummy secretion. They are grouped, side by side, length- 

 wise within the cocoon of the moth. I would state in this connection that 

 one of my Cecropia cocoons contained a number of parasitic larvae, 

 apparently half fed, starved out, dry and hard. I make this note in view 

 of the remarkable instinct that governs this family in commonly providing 

 the necessary food for its progeny. The insufficiency in this case is pos- 

 sibly accounted for in that the caterpillar may not have been full fed at the 

 time of spinning its cocoon, and that the parasite, with an instinct as to 

 quality, but not quantity of food, and following the habit of many gen- 

 erations, makes a deposit of ova in correspondence with the ordinary size 

 or common growth of the caterpillar. The pupa of P. Achemon gives me 

 twelve cocoons of Perilampus ; they are of a dark brown color, about a 



