130 
Journal New York Entomological Society. 
[Vol. V. 
A COMPARATIVE STUDY OF SEVEN YOUNG 
ARCTIANS. 
PLATES VII AND VIII. 
By Harrison G. Dyar, Ph. D. 
The larvae of the Arcticans, including in this term both Arctiidae 
and Euchromiidae, are much more highly specialized than those of the 
Noctuidae. This specialization tends to force back into the first stage 
certain characters properly belonging to the later stages, and it is pro¬ 
posed to briefly consider some of the forms which this modification of 
stage T assumes. 
The arrangement of the tubercles in stage I of the Arctians corre¬ 
sponds with that normal for the whole group Bombycides.* The setae 
are of the finely spinulated type, with pointed tips, never glandular, in 
this respect distinguished from the Ptilodontidae (Notodontidae) 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), A. antigone (Fig. 2) and Hyphantna 
cunea (Fig. 3); from the Phaegopterid group, Halisidota maculata 
(Fig. 4) and H. caryce (Fig. 5); from the Euchomiidae Cosmosoma 
auge (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 Euchromiidae, 
however, do differ to this degree, the special character being the union 
of setae ia, ib and iia on thorax to form a single wart. In Halisidota 
* 7 . e ., 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. 
