1890.] 
499 
[Packard. 
lars, and it is well known that naked or slightly piliferous larvse 
are more subject to their attacks than those which are densely 
hairy or spinose. 
The eruciform type oflarvce . — In endeavoring to account for the 
origin of the tubercles and spines, as well as the hairs of cater- 
pillars, let us glance at the probable causes of the origin of the 
caterpillar form, and of the more primary colors and markings of 
the skin. 
It was Fritz Muller who in his Fur Darwin (1864) maintained 
that “ the so-called complete metamorphosis of insects, in which 
these animals quit the egg as grubs or caterpillars, and afterwards 
become quiescent pupae, incapable of feeding, was not inherited 
from the primitive ancestor of all insects, but acquired at a later 
period. 1 
In 1869, Dr. F. Brauer 2 divided the larvae of insects into two 
groups, the campodea-form and raupen-form, and in 1871 3 -73 we 
adopted these suggestive views, giving the name of eruciform to 
the larvae of weevils and other coleopterous larvae of cylindrical 
form, as well as to the larvae of Diptera, Lepidoptera and Hymen- 
optera, all of which are the result of adaptation, being deriva- 
tives of the primary campodea type of larva. Brauer’s views on 
these two types of larvae were also adopted b} T Sir John Lubbock,, 
in his Origin and Metamorphoses of Insects, 1873. 
While the origin of the eruciform larvae of the Cerambycidae, 
Curculionidae, Scolytidae and other wood-boring and seed-inhabiting 
and burrowing Coleopterous larvae in general, is plainly attribu- 
table to adaptation to changed modes of life, as contrasted with 
the habits of roving, carnivorous, campodeiform larvae, it is not 
so easy to account for the origin of the higher metabolous orders 
of Diptera, Lepidoptera and Hymenoptera, whose larvae are all 
more or less eruciform. We are forced to adopt the supposition 
that they have independently originated from groups either be- 
longing to the Neuroptera (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 
3 Facts and arguments for Darwin, with additions by the author. Translated from 
the German by W. S. Dallas, F. L. S. London, 1869. 
2 Betrachtungen iiber die Yerwandlung der Insekten im Sinne der Descendenz- 
theorie. Verh. K. K. Zool. bot. Ges. Wien, 1869. 
3 American Naturalist, Sept., 1871. Embryology of Chrysopa. 
