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SATURN!DAE. General Topics. By Dr. M. Draudt. 
southernmost parts of Chile, where the re-occurrence of northern forms after crossing the southern tropic is 
less conspicuous than is the case in Africa, where it marks a most characteristic feature. It is just in Argentina 
and Chile, where we still come across very remarkable and variegated representatives both among the real 
Saturnidae (Polythysana) and among the Syssphingidae (Dysdaemonia fosteri), although the number of forms 
decreases considerably to the north and south. The tropics of America certainly contain the greatest variety 
and an incredible abundance of species. 
Real protective colourings are less common with the American forms than for instance in the African 
Region, where it is an especially characteristic feature of the Carnegia and Ludia. Beside the peculiar 
Neocarnegia basirei which resembles a crumpled withered leaf with many holes in it, there are only the green 
forms of Tropaea which are rather imperceptible among the green leaves. Moreover, we may mention yet the 
Lonomia- species copying yellow or brownish leaves provided with rusty or spore-like spots, mostly even with 
a brown median vein, as well as most of the Automeris which look like withered leaves, when at rest. 
By far the most of the Saturnidae are “defiant forms” which, by means of their often strikingly 
developed frightening eyespots, are undoubtedly able to frighten off small-sized enemies. If one has seen, 
for instance, the large Automeris metzli opening and closing its hindwings on being disturbed, as butterflies 
do, and displaying the enormously developed eyespot, one may easily imagine that to a certain degree it is 
protected by this and still more so by its large size. 
Of the larvae of the American Saturnidae we know relatively much, quite a number of them having been 
bred in Europe and being, therefore, well known. The larvae of Automeris are apparently particularly protected 
by their often very effectively burning hairs. The larva of janus, for instance, is enveloped in so dense a prickly 
armour of horribly burning hairs that it may cause very dangerous injuries. As in other faunal regions we also 
often find here very brightly variegated warning colours, the insects frequently being green with variegated 
warts on black belts. 
A unique position is occupied by the Syssphingid larvae, above all the Arsenurinae. We find here the 
same or quite similar conditions as were described with the family of the Brahmaeidae. They are remarkably 
soft animals, in their youth with large horns in front and behind, which mostly disappear with their later 
moults. The best example for this group is the well known “hickory-devil” (cf. picture on cover). 
The food-plants of the American Saturnidae are chiefly all kinds of foliage-trees, frequently fruit-trees. 
Already in the Indian Part it was mentioned that, for instance, the larva of PI. cecropia occurs on many species 
from about 20 different families of plants, being thus extremely polyphagous. Wherever large species occur 
in great numbers, they may, owing to the great voracity and the quick growth of the larvae, defoliate whole 
trees and forests. This, however, is not only known of the large species of Sarnia and Telea, but also smaller 
animals, such as some Hylesia, e. g. //. nigricans Berg from Argentina, may do enormous damage to fruit-trees or 
willow plantations. There are, however, also herbivorous larvae, for instance among the Hemileucidae a whole 
group living on grass, which may sometimes devastate pasture-land, if they occur in great numbers, as it was 
ascertained for Euleucophaeus oliviae. The quite different Oxytenidae live on Rubiaceae. The Saturnidae 
apparently do not live on real poisonous plants, as has also been ascertained in reference to the other faunal 
regions. 
Many species are known to live gregariously in their larval stage, for instance several species of Hylesia, 
some of which set out in lines in search of their food like our processionary caterpillars, in order to return again 
to their common nest. Others, such as Dirphia gregatus, build a solid nest similar to that of the Pierid Eucheira 
socialis (Vol. V, p. 55) in the shape of an oval bag of 15—20 cm length, which being open at both ends, is 
fastened to the end of a twig with a stalk and to which adjoining leaves are drawn ; in this nest also the pupation 
takes place in separate cocoons. 
The way of pupating does not differ from the usual scheme, as far as the genuine Saturnidae are con¬ 
cerned, all of which build cocoons of a rather coarsely or densely matted meshwork which is often even wrapped 
lip in leaves and, in certain species, suspended on a thread. No American species supplies really useful silk, 
it has occasionally been tried to utilize the cocoon-silk of Ph. cynthia and C. promethea, but it cannot be 
reeled off. With the exception of the Telea and Tropaea, which are externally and also biologically very closely 
allied to the Saturnidae, the Syssphingidae pupate without a cocoon naked in the soil. The entirely different 
Oxytenidae, whose larvae recall Sphingid-like types, pupate with few threads between rolled-up leaves, 
whereas the Cercophaninae, more like the genuine Saturnidae, weave oval or more pear-shaped cocoons which 
are open at one or both ends. 
