130 Journal New York Entomological Society. [Voi. v. 



A COMPARATIVE STUDY OF SEVEN YOUNG 

 ARCTIANS. 



plates vii and viii. 

 By Harrison G. Dvar, Ph. D. 



The larvse of the Arcticans, including in this term both Arctiidae 

 and Euchromiidte, are much more highly specialized than those of the 

 NoctuidK. This specialization tends to force back into the first stage 

 certain characters properly belonging to the later stages, and it is pro- 

 posed to brieily consider some of the forms which this modification of 

 stage r assumes. 



The arrangement of the tubercles in stage I of the Arctians corre- 

 sponds with that normal for the whole group Borabycides.* The setae 

 are of the finely spinulated type, with pointed tips, never glandular, in 

 this respect distinguished from the Ptilodontidse (Notodontidce) and 

 certain lower Tineid genera, as pointed out by Dr. Packard. The 

 seven species taken to illustrate this paper, represent three unequal 

 groups of the Arctian phylum. From the Arctiidae proper I have taken 

 Spilosoma virginica (Fig. i), S. afitigone (Fig. 2) and Hyphantria 

 cunea (Fig. 3); from the Phsegopterid group, Halisidota inacidata 

 (Fig. 4) and H. caryce (Fig. 5 ) ; from the Euchomiidae Cosmosoma 

 ai/ge (Fig. 6) and Ctenucha virginica (Fig. 7). I have arranged 

 these as nearly as possible in ascending order of specialization, and it 

 will be noticed how exactly this corresponds with the arrangement 

 founded on the wing veins of the imago. That is, the Spilosoma group 

 represents a more generalized type than the Halisidotas, the latter hav- 

 ing reduced secondaries and shortened subcosta, whereas in the Euchro- 

 miidae subcosta is entirely absent. The degree of difference of these 

 groups also is the same in both larva and imago. While the larval 

 Halisidotas are more specialized than the Spilosomas, they do not differ 

 from them enough to determine family characters. The Euchromiidte, 

 however, do differ to this degree, the special character being the union 

 of setce ia, ib and iia on thorax to form a single wart. In Halisidota 



* /. <?., the Noctuina as defined by me or Agrotides of Mr. Grote. I find that 

 these names must be replaced by the old term Bombyces or Bombycides, because 

 Bombyx really belongs to this superfamily, and not to the Saturniides, as I formerly 

 supposed, following the conclusions of Professor Comstock. I have recently made a 

 careful examination of stage I of Bombyx, at the suggestion of Mr. Grote, with the 

 above result. 



