28 PROCEEDINGS OF THE ACADEMY OF 



under my notice. Eacles imperialism Hiibner, was, a few years ago, 

 always to be looked for upon coniferous plants. During the last 

 three years but few individuals have been observed upon plants of 

 this family ; for every one feeding thereon, scores have been taken 

 from Acer rubrum and A. saccharinum : occasionally from the En- 

 glish walnut, Juglans regia. Citheronia regalis, Fabr., upon Acer 

 rubrum. Platysamia cecropia upon Mibes rubrum, Acer rubrum, 

 A. saccharinum, and Pyrus mains. Other examples might be cited, 

 but enough have been adduced for the writer's purposes. In the 

 cases of regalis and imperialis, alterations in larval structure 

 have occurred, as diminution in size, smaller development of spini- 

 ferous tubercles, color variations to a limited degree ; and in case 

 of imperialis particularly, comparative smoothness of body, very 

 few hairs being noticeable. Still further changes have been ob- 

 served. It is stated in books that many larva? which enter the 

 ground preparatory to assuming the chrysalis form, ordinarily 

 construct earthen cells which they line with a thin la3'er of silk, 

 and subsequently coat with a varnish-like secretion, to render 

 them impervious to water. That this is only occasionally so, I am 

 satisfied from years of experience. That regalis and imperialis 

 enter the ground is the common experience of lepidopterists ; but 

 it is not necessarily so. In many instances, I have witnessed the 

 change effected near the surface of the soil, within a slight cavity 

 which the larvae by their motions had created, and with considerable 

 portions of the upper surfaces exposed. Again, the change has 

 occurred upon the surface of the soil, without even the slightest 

 attempt at cell-making being manifested. It is necessary to state in 

 connection herewith, that the larvae were amply provided with earth 

 of the proper consistency, so there could not have been, as far as 

 could be discerned, any obstacle to the fulfilment of their usual habit. 

 Thyreus Abbottii in the chrysalis form has been found reposing 

 upon the surface of the ground underneath the shelter of a culti- 

 vated variety of Vitis cordifolia, Mich., in a very open and ex- 

 posed situation ; undoubtedly the identical spot which the larva 

 reached after separating itself from its favorite food-plant, was 

 the scene of its assumption of the chrysalis state. This circum- 

 stance appears curious and unique, in view of the fact that ordi- 

 narily there is a disposition upon the part of larvae to seek seques- 

 tered situations. 



After this rehearsal of facts to show that the surroundings of a 



