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VOL. XXVII. LONDON, APRIL, 1895. No. 4. 



VARIATION IN NEMEOPHILA PETROSA AT LAGGAN IN 



WESTERN ALBERTA. 



BY THOMAS E. BEAN. 



At 5,000 feet altitude, in the vicinity of Laggan, Nemeophila petrosa 

 flies during July. This is one of our commoner moths, and appears to 

 be the only bombycid of common occurrence in the district. Although 

 occasionally found near timber line, it is rare at that elevation. Under 

 natural conditions only one flight occurs in the season, and larvae from 

 eggs of that flight hibernate principally at an early stage. In the house, 

 with a warmer night temperature, larva? resultant from the July flight will 

 go to imago late in October instead of hibernating. In the wild environ- 

 ment, a second flight is prevented by the low night temperature. Petrosa 

 frequents moist banks, ditches, margins of old roads, and open ground 

 well supplied with plants. A great majority of the individuals seen in 

 flight are males, the disparity in relative number of males and females 

 observed resulting from the quieter disposition of the females. The 

 males are very restless and readily take flight, thereby attracting observa- 

 tion. The females, less demonstrative, fly but little and are seldom 

 noticed. Males, the physiologists kindly inform us, are katabolic, and 

 females anabolic ; we may discover, unaided, that the terminology is 

 diabolic. Results obtained by bringing to imago a large number of wild 

 larvie and pupse indicate that the females of Petrosa somewhat out- 

 number the males. The larva is a general feeder, thriving on aster, 

 strawberry, or grass, and extremely partial to the newly formed pupa of 

 Nemeophila petrosa. 



The plate which this notice is intended to explain and supplement has 

 been prepared under the skillful supervision of Mr. H. H. Lyman. 

 Selection of specimens for the purpose proved a difticult matter, on 

 account of the necessary limitation to a single plate of twenty figures. 

 Complete illumination of the subject would require at least five plates. 

 Were such ample resources of illustration available, three of the plates 

 would serve to present effectively the principal sequence of pattern 



