Packard.] 
496 
[Feb. 19, 
concealment, between leaves, or in buds, or as miners, that they 
differ little in their surroundings from the low-feeding forms, and 
are thus scarcely ever tuberculated or spiny ; in fact, we cannot re- 
call one of these groups which are so. The Pterophoridse are to 
be sure spiny, but they are low-feeders, and their peculiar excretory 
setae (the driisenharchen or glandular hairs of Zeller 1 ), are similar, 
as Dimmock has observed, to the glandular or long hairs of plants, 
Miss Murtfeldt adding that “ there is a very close imitation in the 
dermal clothing of the larvae [of Leioptilus sericidactylus ] to that 
of the young leaves of Vernonia, on which the spring and early 
summer broods feed.” (Psyche m, 390, 1882). 
Returning to the Bombyces, all the Notodontians, without any 
exception known to us, have trees as their principal, if not exclu- 
sive, food plants. Thus, of the thirty-seven species of this group, 
whose larval forms are known, and which are enumerated in Mr. 
H. Edwards’ “ Bibliographical catalogue of the described transfor- 
mations of North American Lepidoptera,” together with an ad- 
ditional species ( Ichthyura strigosa ) omitted from the catalogue, all 
are known to feed on trees, unless we except Datana major , which 
feeds on Andromeda, and Schizura musteliha , which Professor 
French has thus far only found feeding on the rose ; and these are 
shrubs. It is noteworthy that the only species found thus far on 
an herbaceous plant is the caterpillar of Apatelodes torrefacta , 
which Harris found on the burdock, though usually it is an arbo- 
real insect. This apparently omnivorous feeder resembles the 
species of Halesidota, all of which occur more commonly on trees 
than on herbs, and thus differ markedly from the majority of the 
Lithosians and Arctians, unless we except the Nolidae. Now the 
larva of Apatelodes is hairy, the long, white hairs having scattered 
among them black ones, with more or less black pencils, thus 
resembling the peculiar yellowish or white caterpillars of Halesi- 
dota, with their black tufts and pencils. Similar forms are some 
of the arboreal, hairy Noctuidae, as Gharadra deridens. It seems 
evident that the resemblance to each other in such different groups 
is the result simply of adaptation, brought about by two factors, 
the primary one being a change from a low-feeding to an arboreal 
station, and consequent isolation or segregation, and the secondary 
one being natural selection, the latter further tending to preserve 
the specific form. 
Revision der Pterophoriden. Linnasa entom., 1852, vi, 356. Mentioned by Dimmock. 
