March, 1902.] SeIFERT : NORTH AMERICAN ArCTIIO^E. 7 



of variability of a species. A trial in this respect was made with one 

 generation of nais, though evidently the food-plant could be of no 

 concern to such a polyphagous species. 



Four females, all with red hind wings, were exposed May 17th and 

 ]8th in Long Island and Westchester Co. One part of the newly- 

 hatched larvae were reared solely on Taraxacum and Plantago ; an- 

 other part was fed on Rumex acetosella and the remaining third on 

 Artemisia ahsynthium. I'he result was that those larvae reared on 

 Taraxacum and Plantago developed in the most satisfactory manner, 

 the imagines including all varieties in perfect examples ; while the 

 part raised on Rumex. acetosella gave also the varieties in the same 

 proportion as the first part, but every one of the number behind the 

 regular size and of sickly appearance ; tho.se fed on Artemisia absyn- 

 t Ilium all died before pupating. 



In ^. nais male and female the costal margin is always black and 

 even with the varieties which have the ^ mark most complete, this 

 latter never impairs the black costal margin. The subcostal and sub- 

 median longitudinal stripes are in both sexes often much reduced, the 

 former sometimes not reaching transverse posterior band, the latter 

 forming a fork with the median longitudinal band, which always reaches 

 to transverse posterior stripe. 



The males of nais have pale ochre yellow secondaries, often more or 

 less tinged with reddish, the red color always originating from root 

 of wing, streak-like, most profuse generally near abdominal margin. 

 Originally perhaps the hind wings of the male had a black marginal 

 band, as many of the females have now, but with the many hundreds 

 reared under normal conditions and seen elsewhere in collections, this 

 band is always dissolved into spots, often reduced to dots and some- 

 times obliterated altogether exce|)t one large, black apical spot at- 

 tached to the costal black shade. Comparing a large series of both 

 males and females, the breaking of the marginal band seems to origi- 

 nate right below apex by the fork-like inroad of the ground color, sep- 

 arating at first the band in three unecjual parts ; the thus acquired 

 character may be aggravated by transmission. 



The females either have deep ochre -yellow or red hind wings, some- 

 times, but not frecjuently suffused ; they are either bordered by a 

 black marginal band or this is broken into three or more prominent 

 spots of unequal sizes. The band is nearly always, though often very 

 slightly, inverted below apex, the ochre or red color forming a tooth- 



