14 
MEMOIRS OF THE :N-ATI0NAL ACADEMY OF SCIENCES. 
While the origin of the eruciform larvje of the Ceraiuoycidiej Curculionidie, Seolytidie, aud 
other wood-boring and seed-inhabiting and burrowing Coleopterous larva3 in general, is plainly 
attributable to adaptation to changed inodes of life, as contrasted with the habits of roving,, 
carnivorous, cam pod ei form larvae, it is not so easy to account for the origin of the higher metabolous 
orders of Diptera, Lepidoptera, and Hymenoptera, whose larvie are all more or less eruciform. We 
are farced to adojit the supposition that they have independently originated from groups either 
belonging to the ^5’euroi)tera (in the modern sense) or to some allied but extinct group. 
Restricting ourselves to the Lepidoptera; as is well known the Lepidoptera are now by some- 
believed to have descended from the Trichoptera or from forms allied to that group. We should, 
however, iirefer the view that the Lepidoptera, Trichoptera, and Mecoptera had a common origin 
fiom some earlier, extinct group. The similarity of the imagines of certain of the lower Tineina 
and certaiu of the smaller Trichoptera is certainly very marked, the most significant feature being- 
the fact that the mandibles in the two groups are either absent or minute aud rudimentary. 
We have attempted, however,^ to show that the larvm of the Panorpidie, judging fromBrauer’s 
figures aud descriptions, are much nearer in shape and ornamentation to caterpillars than to 
case Avorms, Hence, it seems to us probable that the ancestral or stem form of the Lepidoptera. 
was probably a now extinct group, somewhat intermediate between the Mecoptera (Panor])idie) 
and the Trichoptera. 
The prmitivG caterpillar, — We Avould suggest that the earliest type of Lepidopterous larva 
Avas allied to some Tineoid which lived not only on land but on Ioav herbage, not being a miner or 
sack-bearer, as these are evidently secondary adaptive forms. It is evident, when Ave take into 
account the remarkable changes in form of certain mining Tineoid larvm described and figured by 
Chambers 2 and by Dimmock,^ that the flattened, footless, or nearly apodous mining larvie of the 
earlier stages are the result of adaptation to their burrowing habits. The generalized or primitive 
form of the first caterx)illar Avas, then, like that of Tineoid larvie in general, aud Avas an external 
feeder rather than a miner. The body of this forerunner or ancestor of our present caterpillars- 
(which may have lived late in Carboniferous times, just before the appearance of flowering plants 
and deciduous trees) was most probably cylindrical, long, aud slender. Like the Panorpid larvie, 
the thoracic and abdominal legs had already becom differentiated, and it differed from the larvie 
of Panorpids in the plautie of the abdominal legs being provided Avith j)erhaps tAvo pairs of 
crochets, thus adapting them for creeping with security over the surface of leaves and along twigs 
and branches. The x)rothoracic or cervical shield Avas present, as this is axiparently a primitive 
feature, often reaxApearing in the Noctuidie, aud sometimes in the Bombycina, and ahvays lAresent 
in the boring larvie of the Hexnalida; and the Cossidte. 
As tactile hairs, defensive or locomotive setie, aud si)iues of manifold shax^es occur in AA'orms, 
often arising from fleshy Avarts or tubercles, it is reasonable to assume that the xnliferous Avarts of 
lepidoiAterous larvm are a direct heirloom of those of the vermian ancestors of the iusects. In our 
primith’-e caterpillar, then, the x>iliferous Avarts Avere i»resent, eventually becoming arranged as 
they now are in ordinary Tineoid, Tortricid, Pyralid, Geometrid, and Xoetuid larvie. 
Origin of the green color of caterpillars . — The cuticle may at first, as in that of caseworms and 
Panorind larvie, ha\^e been colorless or horn colored. But soon after habitually feeding in the 
direct sunlight on green leaves, the chlorophyll thus introduced into the digestive s^^stem and 
into the blood and the hypodermal tissues would cause the cuticle to become green. AfterAAUirds, 
by further adaptation aud by heredity this color would become the hue in general common to- 
caterpillars. Moreover, some of the immediate descendants of our jwimithm cateri)illars were 
probably lighter in hue than others; this was probably due to the fact that the lighter-colored ones, 
fed on the x^fil^-g'reen underside of the lea\^es, this difference becoming transmitted by heredity. 
‘ Third Report U. S. Entomological Commission. Genealogy of the Hexapoda, pp. 297-299, 1883. Also American 
Naturalist, Sept., 1883,932-945. 
2 American Entomologist, iii, 1880, 255-262; Psyche, ii, 81, 137-227; iii, 63, 135, 147; iv, 71. Refers to the larvm- 
of the •‘Gracilaridie^' aud “Lithocolletidie^^ together Avith Phyllocnistis. 
3 Psyche, iii, Aug., 1880, 99-103. 
•* See the important and quite conclusive footnote by Professor Meldola on j). 310 of AA’^eismaim’s StuiUes in the- 
Theory of Descent. Vol. i (‘^I have already given reasons for suspecting that the color of green caterpillars may he: 
due to the jiresence of chlorophyll in their tissues, Proc. Zool. Soc., 1873, 159. — R. 
