36 



little parasite strike the worm with the tip of her abdomen, appa- 

 rently for the purpose of depositing her eggs under its skin. 



At several different times during the past season (1881) I saw a 

 few of these parasites quietly resting upon the back of a Cabbage 

 Worm which had suspended itself prior to assuming the chrysalis 

 form ; but at such times I never saw any of them make any attempt 

 at depositing eggs. After the worm had cast its skin, however, and 

 the chrysalis is yet soft, I have, on two or three occasions, seen one 

 of the parasites bend the tip of her abdomen downward until it 

 pressed against the chrysalis, and hold it there for a few moments, 

 apparently for the purpose of depositing her eggs in the chrysalis. 

 The part of the chrysalis which the parasite usually selects for de- 

 positing her eggs into, is one of the wing-cases, although she some- 

 times consigns them to the back of the abdomen. 



On the 13th of September I saw several of these parasites issue 

 from a chrysalis. The sexes emerged from two different holes in 

 the chrysalis ; the large, dark-colored females issued from a hole in 

 the right wing-case, while the smaller but brighter-colored males 

 issued from a hole in the back of the abdomen. Coition took place 

 immediately after they had issued, and lasted about ten seconds, 

 after which the females flew away, but the males remained, looking 

 out for another victim. The copulating orifice of the female, instead 

 of being at the tip of the abdomen, as it is in most insects, is situ- 

 ated in the middle of the under side of the abdomen. 



I have never met with the Purple Cabbage Worm {Pioiiea rimo- 

 salis, Guenee,) which Prof. Thomas found feeding upon his cabbages, 

 and which he gives an account of in his Fourth Pieport.* The past 

 season a closely allied species — the Pionea strameiitalis of Hubner — 

 appeared in considerable numbers upon the Horse-radish in this 

 vicinity. As almost every insect which feeds upon this plant will 

 also feed, upon the cabbage, it is very probable that this insect will 

 also be found to feed upon this vegetable ; • and for this reason I 

 have thought it best to insert a brief account of it in this place. 

 The worms referred to above are provided with sixteen legs, and 

 are marked as follows : There is a yellow stripe on a line with the 

 spiracles, and below this stripe the body is pale-green ; above this 

 stripe the body is pale greenish-purple, and is marked on the back 

 with two broken white lines ; the piliferous or raised spots are of a 

 polished black color, and are usually marked at the base with a 

 Avhite spot on the upper and lower side of each ; the head is polished 

 black, the cervical shield is greenish, and is marked with black on 

 each outer edge ; the spiracles are wholly black. 



When fully grown, these worms measure about three-fourths of 

 an inch in length. Should they ever become destructive to the Cab- 

 bage, they may be known as the Black-headed Cahhage-worms. 



From the description of the Purple Cabbage-worm given by Prof. 

 Thomas in the report referred to above, it will be seen that this 

 worm differs from those described above, by having that part of the 

 body which is above the stigmatal yellow lines of a purplish -brown, 

 instead of a greenish-purple color, and the head, instead of being 

 polished black, is there stated to be greenish-yellow. In other re- 

 spects, these two species approach each other very closely. When 



* Ninth Annual Report of the State Entomologist of Illinois, page 37. 



