148 BULLETIN UNITED STATES GEOLOGICAL SURVEY. 



of Tineina is dependent upon that of a single plant-species, and conse- 

 quently in passing above timber-line Tineina might be expected to 

 become exceedingly rare. In point of fact, I found none except the 

 Gelechia larva on willows before mentioned, and in all probability that 

 species will be found also far below timber-line. Harden, if I remem- 

 ber aright, gives 11.770 feet as the height of timber-line on Mount 

 Elbert. 



The I'terophorus observed by me as above stated was probably P. 

 cinereidactylus, which has been taken in the mouu tains of Xew Eng- 

 land ; and it is to be regretted that I did not succeed in taking it, so 

 that this fact might have been determined; and that it might also be 

 determined whether it differs in size, in relative length of peripheral 

 parts, or in depth or intensity of color, from the New England speci- 

 mens. Dr. Packard's observations (loc. cit.) tend to establish the rule 

 that the western species are larger, with greater relative development 

 of peripheral parts, and greater depth and intensity of color than their 

 eastern congeners ; and in view of his observations, and those of Mr. 

 "Wollastou and others, on insects of other orders and of other countries, 

 and in consideration of the bright sunlight and prevailing high winds 

 in Colorado, 1 had expected to find the rule confirmed among the Tine- 

 ina, or else to have found a much larger proportion than usual of 

 apterous species, since the bright light would tend to develop color; 

 and either the absence of the power of flight, or its greatly-increased 

 development, would tend to the protection of species against atmos- 

 pheric influences. But I found nothing to confirm these views. On the 

 contrary, so far as color is concerned, the Tineina of Colorado, and, so 

 far as I have had an opportunity of observing them, those of California 

 likewise, are plainer and more obscurely colored than those of the Mis- 

 sissippi Valley ; and, so far as size and extent of peripheral parts is con- 

 cerned, the individuals, when they belong to species found also in the 

 Mississippi Valley, differ usually in no respect from those found in the 

 latter region : and when species are allied to eastern species, they do 

 not differ from them more than eastern species differ from each other. 

 Thus the 9 Tinea and allied genera are frequently apterous iu the 

 States and in Europe; but I saw only a single Tinea (damaged beyond 

 recognition) in Colorado, and that was not apterous, nor was there any 

 unusual development of the wings or other peripheral parts. Tinea 

 appears to be but poorly represented there. The average size of 

 Tronuba yuccasella Riley, in Colorado, is less than that given for 

 it by Mr. Eiley in Missouri: and it differs from Missouri and Ken- 

 tucky specimens ouly in the fact that a large number of speci- 

 mens have small black spots on the fore wiugs. Ryponomeutida- 

 are represented by numerous specimens of two species of Anesyehia, one 

 of which {A. mirusella Cham.) is common in Texas: they give no sup- 

 port to the theory. Plutella cruciferarum is, in Mr. Staiutons's lan- 

 guage, '•found wherever man eats cabbage", and it appears to be the 



