OF THE STATE ENTOMOLOGIST. 131 



just before pupating, and to abandon their dry food for that which is 

 more green and succulent. 



As this insect has never been found in large numbers, and con- 

 tents itself during most of its life with that which is valueless to us, 

 it can not be considered as injuri(4us ; and I have introduced it to my 

 readers rather on account of its curious life-history than because of 

 the few sumach leaves which the beetle riddles. 



THE YUCCA MOTll—Promcha yuccasdla Riley. 



My observations of the past year have enabled 

 me to complete the natural history of this curious and 

 interesting insect. Regarding the chrysalis, I extract 

 the following from the Transactions of the St. Louis 

 Academy of Science (Vol. III., p. 178) : . 



''As I suggested it would, the larva remains in its 

 cocoon unchanged all through the fall, winter and 

 spring monl hs, and does not assume the chrysalis state 



PjiOXDBA yUCCASEL- ^ -i ^ 



i^m7/echrvl^aiis'"' ^^^^ ^ fortnight or so before the blooming of the Yuc- 

 cas. 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 afterward 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 through 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 origi- 

 nal length. 



• " Description of Chrysalis, § (Fig. 38, to, lateral view).— Averaoe length 0.30 

 inch ; greatest diameter about 3-7 the length. Thick and stout, with the dorsum 

 greatly arched. Head with a prominent, conical projection 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 ante- 

 riorly 10-12 blunt, flattened, recurved projections, the largest in the middle, from whicli 

 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 forward ; all which features are 

 gradually lessened with each succeeding joint. Joint 11 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 trans- 

 verse series of stiff yellow hairs, and four such are quite conspicuous on niesothorax, 

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

 sheaths darker. When mature, and just before giving forth the moth, the head, tho- 



