160 REPORT OP THE STATE ENTOMOLOGIST. 



species may be benefited thereby. Now the blooming season of our 

 Yuccas is comparatively brief, and it is quite evident that those Pro- 

 nulas^ which do not issue within the appropriate time, must perish 

 without leaving progeny. We might, therefore, expect to find the 

 habit of issuing at the proper season, inherited through no one knows 

 how many generations, very strongly fixed and diflicult to break up ; 

 and such is the case to a remarkable extent. Some insects I have had 

 no difficulty in forcing or causing to give out the imago prematurely, 

 by submitting them to artificial conditions of heat and moisture. Not 

 so with Pronula ! for, while I was quite anxious to breed a few to 

 the chrysalis state before publishing this Report, and, for that purpose, 

 kept a number at a mean temperature of about 80° all through the 

 winter, every one of them is, at this writing, (April 10th), yet in the 

 larva state. 



Thus my inference, that it hibernates as larva, proves correct, and 

 we may likewise infer that the chrysalis will be furnished with teeth 

 or spines, by aid of which to work itself to the surface of its earthy 

 shroud. 



The following extract from a letter by Mr. H. T. Stainton, of Eng- 

 land, and dated September 25th, 1872, will prove valuable as the 

 opinion of our greatest micro-lepidopterist : "The Ptonuha yucca- 

 sella is a most curious insect. The bare, horny hinder segments of 

 the female remind me of some of the females of the genus of Long- 

 horns jVemotois, such as scahrosellus, which lays its eggs at the bot- 

 toms of scabrous flowers, where a thickly scaled abdomen would be 

 ill-suited to its purpose. The remarkably bull-headed appearance of 

 your yuGcasella is very striking, and the more I look at the creature 

 the more puzzled I seem as to its affinities. We have no European 

 genus at all analogous."] 



