178 



TRANS. Sf. LOUIS ACAD. SCIENCE. 



Supplementary Notes on Pronuha Yuccasella. 



Bj Chas. v. RiLHY, M.A. 



[Fig. 3.] 



In the paper on this insect which was com- 

 municated to the Academy last fall, and which 

 is now in print, the latter part of the natural 

 history of Promiba^ as there given, needs to be 

 substantiated ; and I now take pleasure in sup- 

 plementing and completing it. 



As I suggested it would, the larva remains 

 in its cocoon unchanged all through the fall, 

 winter and spring months, and does not as- 

 sume the chrysalis state till a fortnight or so before the bloom- 

 ing of the Yuccas. It is one of the hardiest larvae I have had 

 to do with, and will not only repeatedly mend its cocoon when 

 this is cut or torn, but, when extracted from it, will survive for 

 months if afterwards kept in a tight vessel. This tenacity of life 

 makes its safe transportation from one country to another all the 

 more sure and easy. 



The chrysalis works its way througn a long dorsal rent in the 

 larval skin, so that this latter is not compressed into a little mass, 

 as is the more usual way with Lepidoptera^ but retains nearly 

 its original length. • 



Description of Chrysalis, $ (Fig. 3, /«, lateral view). — Average 

 length 0.30 inch ; greatest diameter about f the length. Thick and stout, 

 with the dorsum greatly arched. Head with a prominent, conical projec- 

 tion on top, and two smaller ones between the eyes. Most characteristic 

 feature a series of six dorsal, arcuated, horny plates — one on the anterior 

 half of each of joints 5-10. These plates have anteriorly 10-12 blunt, 

 flattened, recurved projections, the largest in the middle, from which the 

 others are successively lessened. The ends of some of the larger ones are 

 shaped like the share of the more common shovel-plow. In the first row 

 the arcuation is greatest, and the projections largest and directed most for- 

 ward ; all which features are gradually lessened with each succeeding joint. 

 Joint II has no plate, and but four posteriorly-directed spines, while joint 

 12 has two broad and flattened dorsal processes. Tip of abdomen rounded 

 and reaching beyond the processes. Each joint has a transverse series of 

 stiff yellow hairs and four such are quite conspicuous on mesothorax, and 

 others on top of head and on face. Color when fresh pale green, with the 



