STATE HORTICTJLTUKAL SOCIETY. 



2SI 



Professor French informs me that those he reared remained in the 

 pupa state generally from six to eight days. 



My observations differ somewhat from either of these, showing the 

 time to be shorter. A number of full-grown worms, about twenty, were 

 collected July 17, which were about to enter the pupa state; by the 

 evening of the next day all were chrysalids. On the 22d of the same 

 month, five days afterward, a few butterflies made their appearance ; the 

 23d, a large portion appeared, and in a day or two more all not para- 

 sitized had completed their transformations. It would appear from this 

 that the pupa state is considerably shorter in the latitude of Southern 

 Illinois than in that of New York. 



As the insect winters in the pupa state, the chrysalids of the full- 

 grown brood are not, as a matter of course, transformed into butterflies 

 until the following season — from March to May, according to the latitude 

 and season. The fact that one of Dr. Fitch's specimens entered the 

 pupa state August 21st, and the butterfly did not come out until Decem- 

 ber 8th, and one of L' Admiral's, which pupated September 5th, did 

 not come out until the 28th of May following, shows that in the same 

 section some may be double-brooded while others may be but single- 

 brooded; or in more southern latitudes some double-brooded and others 

 three brooded. 



Miss Smith, in her address delivered before the Wisconsin Horticul- 

 tural Society at Green Bay, states that "the butterflies" (of this species) 

 are generally supposed to hibernate during the winter months. (?) I 

 presume that she intended to convey the idea by this language that it is 

 generally supposed this insect hibernates in the perfect or butterfly state; 

 so far I have been unable to find any authority for this statement, as all 

 the writers who describe the habits of this or the congeneric species 

 state directly or indirectly that they hibernate in the pupa or chrysalis 

 state. This has been known in Europe from the days of Harold, and in 

 America the same fact has been observed from the time of its discovery 

 to the present. 



This species is generally understood to be two-brooded. The perfect 

 insect was taken here last spring early in March and there are a few 

 worms now (Nov. 26) on the cabbages. The butterflies have been more 

 or less numerous all summer, but they appeared to be most abundant at 

 three periods : the spring broods in March and April ; the July brood 

 and September brood. Hence, I feel quite certain that we have had 

 three broods in the southern extremity of the State this year. 



Natural Agencies which assist in its destruction. — Fortunately for the 

 gardener this and the other species of cabbage-butterflies are subject to 

 the attacks of certain parasites which aid very materially in their destruc- 

 tion. Curtis in his ^'Farjn Insects^'' describes and figures several species 

 of parasites which prey upon the three species of cabbage-butterflies found 

 in England, and shows how thoroughly they keep in check these trouble- 

 some worms. These are chiefly minute ichneumon-flies of the Chalcid 

 group, some of which deposit their eggs in the eggs of the butterflies; 

 another punctures the caterpillars and deposits its eggs in its body, while 



