1216 Tin-: buttp:rflies of new England. 



in tlic Hudson Bay region in 1844. The year after Mr. Riteliie, 

 others reared tlie same parasite from P. rapae, and one of the first ac- 

 counts published was one by Master Sprague, then only ten years old, I 

 believe : — 



I was looking for some clirysalids for my father, when I saw a little fly walking all 

 over them ; by-and-by it made a little hole in the chrysalis to lay its eggs in. The fly 

 is almost one-eighth of an inch long; it is of a golden color. Some of the flies have 

 yellow legs, and others have dark ones. They have fonr wings; the body is pointed 

 at the end ; there are about fifty of these flies in a chry.salis ; the chrysalis looks as if 

 it were all right; bnt if you break it open yon will find it full of little grubs. (Can. 

 ent., Hi: 235.) 



Some years later we iiave the following account of the operations of this 

 insect, by a well knotvn observer : — 



A few days since, while watching some of the full grown larvae of the cabbage 

 butterfly, which were feeding on Nasturtium leaves, I was much gratifledin witnessing 

 the method of attack which this parasite adopts. Settling herself quietly down on the 

 back of the caterpillar, nearthe terminal segments, with her head towards the caterpil- 

 lar's head, she paused awhile; then with a sudden movement of her ovipositor, so 

 quickly that the motion almost escaped detection, she thrust an egg under the skin of 

 her victim. The caterpillar seemed startled, and quivering, jerked Its head and an- 

 terior segments suddenly about, and then quieted again ; the little tormentor meanwhile 

 sitting perfectly composed on the spot where she flrst settled. Presently another 

 thrust was made, followed by further uneasy movements of the larva, and in this 

 manner, in the course of a very few minutes, quite a number of eggs were deposited. 

 The caterpillar did not seem to be conscious of the cause of its troubles, nor, indeed, 

 of the presence of its enemy, excepting when the thrusts with the ovipositor were made. 

 On drawing a little nearer for the jjurpose of better observing this interesting operation, 

 the tiny creatui-e took alarm and flew oil'. Further examination revealed the presence of 

 several more of these little friends, busily searching for further specimens to operate 

 on. (Saunders, Can. ent., x: 185-186.) 



The earlier stages of this parasite are figured by Dr. A. S. Packard in 

 his second Report on the Insects of Massachusetts, and he gives the follow- 

 ing description : — 



The larva is a little white maggot about a sixth (.17) of an incli in length. The 

 body consists of thirteen segments, exclusive of the head, and is cylindrical, tapering 

 rapidly towards the head, while the end of the body is acutely pointed. The clirysa- 

 lis is whitish, the limbs being folded along the under side of the body, the antennae 

 reaching to the end of the wings ; the second pair of legs reaching half way between 

 the end of the wings and end of abdomen; while the tips of the tlilixl pair of feet 

 reach half way between the second p.iir of feet and the end of the abdomen. It is 

 from a line to a line and a third in length. 



The chrysalids of rapae that are infested by them are readily distinguished 

 by the livid appearance of the body, and in the period of greatest abundance 

 of the insect fully two-thirds are found thus attacked. As we have seen, 

 more than a iiundred eggs may be deposited in a single caterpillar without 

 preventing its reaching the chrysalis stage ; and as these may be laid at 

 different times, the parasites may be found in newly formed chrysalids in 

 various stages of growth. Within the chrysalis the parasite winters, and as 



