162 



THE CANADIAN ENTOMOLOGIST. 



In Southern Michigan the life-history of this species in brief is as 

 follows : The eggs are laid during the latter part of July and the first part 

 of August. They are placed on the under side of the leaflets, and drop 

 with the leaves to the ground in the fall, where they remain, more or less 

 covered by snow, until the following spring. I have not gathered the 

 fallen leaves and searched them for the eggs, but that the eggs are there 

 during the winter I can entertain no doubt, a point, however, which I shall 

 hope sometime to demonstrate. The caterpillars emerge from the eggs 

 during the middle of the following April. There are five instars, and the 

 majority of the bred specimens reached the chrysalis between the 15th and 

 the 20th of June, and the butterfly between the 26th of June and the 2nd 

 of July. In the bog I believe these dates would be about two weeks 

 later, as the conditions indoors were probably more favourable to rapid 

 development than they would be outdoors, and this corresponds better so 

 far as my observations have as yet gone with the dates of appearance of 

 the butterflies in the field. This is farther confirmed by the following : 

 Of 14 caterpillars found in a bog near Ann Arbor, I raised 8 to maturity. 

 These yielded butterflies from July i6th to 22nd, dates considerably later, 

 but, on June 13th, 1910, when this lot was secured, all of these caterpillars, 

 except one, were in the third instar, while on the same date nearly all of 

 the egg-bred caterpillars reared within doors were in the fifth instar, many 

 nearly ready for the chrysalis, and two had already changed. It will thus 

 be seen that from the time the egg is laid to the death of the resulting 

 butterfly about one full year is taken. 



I kept records of the time passed in the different instars and chrysalis 

 of as many examples as I could. The table below shows the average 

 number of days passed in the different instars and chrysalis, and also the 

 shortest and longest time spent in any instar or chrysalis. 



Instar. 



First . . . . 

 Second . 

 Third. . . 

 Fourth . . 

 Fifth . . . , 

 Chrysalis 



Number ot 

 specimens. 



41 

 28 

 26 

 26 



27 

 32 



Average num- 

 ber ot days. 



18.6 

 12.3 



8 



10.7 

 13.8 



lO.I 



Shortest time. 



13 



9 



5-5 

 8 



1 1 



8 



Longest time. 



30 

 16 



12 



13 



18 



15 



I should rather have expected that the lengths of time spent in the 

 different instars would have become successively shortened, but instead of 



