12 MEMOIES OP THE NATIONAL ACADEMY OF SCIENCES, 



Of the great group of Geomctridii' iiimiy kiuds are arboreal (l)eudrogeouietrids), and in 

 sucU cases are almost invariably tuberculated in manifold ways. We know of no Lairy or tufted 

 caterpillars of this group or of any family Ijelow tbem, with tlie exception of the Pteropliorida'. 



The arboreal Pyralidst, Tortricidie, and Tineidit live in such 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 can nut recall one of these groups which 

 are sa. The Pterophoridae are, to be sure, spiny, but they are low feeders, and their peculiar 

 excretory seta' (the Driisenhiirchen or glandular hairs of Zeller') are similar, as Dimmock has 

 observed, to the glandular or long hairs of plants; Miss Murtfeldt adding that "thei^e is a very 

 close imitation in the dermal clothing of the larv;v [of Leioptilus .seyicidacti/Iiis\ to that of the young- 

 leaves of Vernouia, on which the spring and early summer broods feed." (Psyche iii, 390, 1882.) 



Returning to the Bombyces, all the Notodontians, without any exception, known to us have 

 trees as their principal, if not exclusise, food plants. Thus, of the 37 species of this group whose 

 larval forms are known, and which are enumerated in Mr. H. Edwards's "Bibliographical catalogue 

 of the described transformations of Nortli American Lepidoptera," together with an additional 

 species {Ichtlii/Krasirigosd) omitted from the catalogue, all are known to feed on trees, unless we 

 except U(tt((na major, which feeds on Andromeda. It is noteworthy that the only species Ibund 

 thus far on a herbaceous plant is the caterpillar of Apatehdcs torrefacUi, which Harris found 

 on the burdock, though usually it is an arboreal insect. This apparently omnivorous feeder 

 resembles the species of Ilalesidota, all of which occur more commonly on trees than on herbs, 

 and thus differs markedly from the majority of the Lithosians and Arctiaus, unless we except 

 the NolidiP. 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 Halesidota, with their black tufts and pencils. Similar forms are some of the 

 arboreal, hairy Noctuida^, as CItaradra 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 pre- 

 serve the specific form. 



It will be seen by the following review that the North American Bombyces in general, with 

 the exception of the Arctians and Lithosians, live on trees, and this will in general apply to the 

 Old World species. In the group of Lasincampidie, represented by Tolype, Artace, Heterocampa, 

 Gastropaciia, and Clisiocampa, the station is an arboreal one, none being known to feed on 

 herbaceous plants. All the Ceratocampida', all tlie Hemileucida' and Attaci, the Platyptericida', 

 all the Cochliopodidie (Limacodes), including both the naked and spiny genera, as well as the 

 Psychidiie, live exclusively on trees. Of onr North American Liparidie, all are arboreal in station, 

 except the t^alifornian Ort/yia rctitsta, which lives on the lupine. Finally we come to the Arctians 

 a id Lithosians, whose hairy, or rather setose, larva; in general feed on herbaceous plants and 

 sometimes on trees, being in many cases omnivorous, while those of the Nolidie and Nycteolidie 

 whose history is known, are arboreal. 



Of the Zygpenidte, including the Ctenucliidie, the species are low feeders, living on lichens, 

 grasses, and other low plants, or upon vines. The Dioptid genus I'hryganidia feeds on the oak. 

 Of the Agaristid.e, some are low feeders, Uuscirrhopterus gloveri feeding on Portulaca, while the 

 majority prefer vines (Vitis, etc.). As to the boring habits, of the Hepialida- and Cossid;e, which 

 we now consider as independent groups, related to the Tineiua, rather than belonging to the 

 superfamily Bombyces, these seem to be the result of early adaptation. 



An examination of the food plants of the British species of Bombyces, taken from Stainton's 

 Manual of British butterflies and moths (1857), gives the same results for the Old World, as will 

 be seen by the following statements : 



that many moths, Notodontians among them, which in the Northern States feed on trec^s alone, in tho Gulf States,, 

 accordiug to Abbott, feed on shrubs, vines, and low plants, as well as trees. 



In reply to an inquiry, Mr. AV. H. Edwards kindly writes me: "I do not think that tlie butterfly larva' which, 

 live on tri'i.'s are under more favorable fonditious than low feeders as to healthiness or fase of rearing." 

 ' Revision der Ptei'ophoriden. Liuu;ea eutora., 1852, vi, 35li. Mentioned by Diuiinock. 



