On Pronuba Yuccasella. 145 



casella there, because thtvt is just the place, and the circumstances and 

 the time when it should be expected to appear. But it is very surpris- 

 ing if the species is a Hyponomeuta, because, for reasons presently to 

 be given, that was just the place and the circumstances in which it 

 ought not to be expected. And j^et, if Mr. Riley is right, and the six 

 specimens seen b}' him being the criterion, not only is a Hyponomeuta 

 found there, in the very domicile of P. yuccasella, hut in numbers Jive 

 to one greater than P. yuccasella itself! — and greatly more numerous 

 than any other species icas found anywhere in Colorado! But wh}^, 

 it ma}^ be asked, ought not we to expect to find a Hyponomeuta in 

 such place and circumstances. 



I have alluded above to the unit}' of habit among species of this genus. 

 Every species of it, of which the larva is known, feeds as larva on ex- 

 ogenous vegetation, is gregarious, and makes much web, Everj' col- 

 lector of these and other Tineina, knows that the place to look for a 

 moth is about the food plant of its larva. I was collecting them daily 

 at a time when I could scarcely have failed to find the web and larvae 

 if they had been there. No trace of either was ever seen in the wood- 

 ed region, nor was a single specimen of the imago found there; nor 

 was an}^ trace of the web or larva found on the plains where the moth 

 was so abundant. If the larva feeds on either j^ucca, cacti or grasses, it 

 can not be gregarious, nor make a web (which I must certainly have 

 found had it existed); and, besides, if it feeds on either of these classes 

 of endogenous vegetation, it is the only species of this (or I may say 

 of an 3' other well limited and established genus of Tineina, such as Hy- 

 ponomeuta) which feeds on an endogen, while all the other species feed 

 on exogens, and is, besides, the only recorded instance of a Hypono- 

 meuta ever seen in a flower of any color! If these specimens, then, be- 

 long to Hyponomeuta, th^y differ tola coslo in habits and habitat, both 

 as larva and imago, from ever}^ other known species of the genus, and 

 not only so, but they violate the unity of habit which prevails so largely 

 among species of so many genera of Tineina; and, already closel}' allied 

 in structure and ornamentation to Pronuba yuccasella, it further 

 mimics it in habit and habitat! A most astonishing case of mimicry'.* 



But Mr. Riley proceeds: " The spots on Hyponomeuta are very vari- 

 able, while some individuals of opunctella are immaculate, when at 

 first sight the}- might be mistaken for Pronuha'"' He has not been 

 particularly happy in the construction of this sentence. It lacks his 



* Mr. Riley gives the expanse of the wings of P. yuccasella 1 in. for the male, and .90 for 

 the female. My Colorado specimens ranged from six to ten lines: twenty specimens, male and 

 female, of the immaculate and undoubted P- yuccasella, taken by me in yucca flowers, in 

 Kentucky, range from ten twenty-fourths of an inch to twenty-one twenty-fourths of an inch. 

 Curious that the imitation should extend not only to the habit, habitat and ornamentation, 

 but even to the variation in size! 



