Annual Address of V. T. Chambers^ Esq. 11 



As to the peiiod of duration of each stage, we shall find, also, that 

 there is great regularit3\ but it is here that the influence of temper- 

 ature is most distinctly felt. Going over the same species above 

 mentioned, and on the authority of the same authors, I find that P. 

 tharos passes 6 days in the egg, 22 in the larva, and 5 in the pupa 

 state, or varying with the season and temperature, 4 in the egg, 22 as 

 larva, and 7 as pupa ; the duration of the egg and pupa together is 

 half that of the larva. But of larva? hatched in the fall, Mr. Edwards 

 found that the time passed in the egg was 5 days, as larva 26 to 37, 

 and as pupa 30 or more days, according to temperature. An effect, 

 perhaps, of the unknown factor I have referred to, was that whilst the 

 general course of development was as above given, yet such larvte as 

 hibernated underwent one more moult than those which passed through 

 all their changes in the same season, perhaps though this was the 

 effect of temperature. The larval life of Z>a»fa'5 arcMppiis lasts from 

 17 to 25 days, according to temperature. The first larval stage of 

 CKnonympha gemma lasts 6 days in April and August, and 9 in 

 October ; the 2d stage lasts 7 days in May, five in August and 10 in 

 October ; the 3d, 5 days in August and 8 in May, and the 4th stage 

 lasts 10 days in August, including two days spent in moulting. Here 

 the larval life extends over such a period, and the duration of the 

 several stages is so complicated by the effects of varjang temperature, 

 that it is impossible to determine how nearly of the same length the 

 several stages would be under the same conditions. Phyciodes nycteis 

 passes 8 da^'s in the first stage in July, and 10 in June ; the 2d stage 

 lasts 4 or 5 days; the 3d, three days; and the 4th three to five days; 

 these variations as in the former case depending upon temperature- 

 But here appears the influence of the " unknown factor," which con- 

 trols the influence of food and temperature. Mr. Edwards states that 

 some larvte of each brood, the early as well as the later ones, ceased at 

 various times to feed and to grow; their development was arrested, and 

 larvae of all the broods spent the remainder of the season, and hiber- 

 nated, in Various stages, and underwent the remainder of their trans- 

 formations the following ^^ear: whilst others passed on regularly 

 through all their stages in the same .year. Something very similar to 

 this occurs, also, with some larvae of Lithocolletis, as will be shown 

 presently. 



Such instances as those above cited show the effect of temperature, 

 but do not so well illustrate the relative lengths of the different stages. 

 But Mr. Gentr}' states that the first moult of the larva of PZc/^?/saw«,'cT 

 cecropia took place June 10th; the 2d, June 18th; the 3d, June 26th; 



