642 THE buttp:rflies of new England. 



certain others which may occur in the later, and the differences as a whole 

 are not so pronounced as in some other dimorphic species, there can be no 

 question in the mind of anyone who has seen large series — the best test of 

 the question — that the differences are valid. I express this opinion the 

 more freely since before the dimorphism w\as known, I had refused to 

 acknowledge the validity of specific distinction between tharos and marcia. 

 There seems, however, in Mr. Edwards's opinion, some tendency to a pre- 

 mature disclosure of the spring form in the last month of the year, as 

 occasionally specimens which must be referred to marcia have been taken 

 very late in the season ; this is a subject worth following up. 



Eisperiments with cold. Mr. Edwards has made two sets of experi- 

 ments : In the first instance on chrysalids from eggs laid by P. t. mor- 

 pheus in West Virginia on August 15, but which were hatched and the 

 larvae raised in the Catskills under protection until September 20, when 

 the chrysalids were placed on ice for seven days and then retransported to 

 West V^irginia ; they all gave P. t. marcia in October. The second 

 experiment was from eggs of P. t. marcia laid in the Catskills, carried to 

 West Virginia and raised there, and the chrysalids placed in an ice-chest 

 at intervals of from ten minutes to nine hours after they were formed ; 

 these were removed after twenty days, and subsequently sixteen butter- 

 flies emerged — all P. t. marcia excepting two, the colors of which were 

 suffused and so indeterminable. 



Enemies. The caterpillar is attacked by the hymenopterous Ichneumon 

 instal)ilis, which emerges from the chrysalis about a fortnight after suspen- 

 sion in the spring, biting off the anterior extremity to make its escape. 

 Mr. Mead reports finding a green spider that had drawn his net about a 

 cluster of the young larvae and "taken up his abode among them, no 

 doubt finding it very convenient to have his prey within such easy reach."' 



Desiderata. Notwithstanding, or rather by reason of, the thorough 

 and extensive breeding experiments of Mr. Edwards more are needed, 

 especially in New England, for New England lies in the direct path of the 

 transition in this species from monogoneutism to digoneutism. In north- 

 ernmost ]\laine, or on the southern shores of the mouth of the St. Law- 

 rence, digoneutism is in all probability a rarity, and a knowledge of the 

 comparative abundance of the two broods at such accessible spots as the 

 towns on the northernmost line of the Intercolonial Railway — Point Metis, 

 Rimouski, or even Cacouna, would be very desirable. If one could there 

 raise under natural conditions of weather-exposure larvae from P. t. mar- 

 cia, note their seasons and watch their behavior, we should, no doubt, 

 learn much of interest. Similar observations for comparative purposes are 

 needed at such places as the White Mountains, Plymouth, N. H., Boston, 

 and New Haven or Nantucket. This and the relation of P. batesii to 

 the present species are the points of greatest importance. 



