SPHINGIDAE. General Topics. By Dr. A. Seitz. 
355 
Most of the Sphingidae often display a monstrous proboscis and are decidedly fond of living on flowers, 
owing to which fact they may also be assigned to the more modern groups of lepidoptera. The Saturniidae entirely 
keep aloof from flowers and exhibit numerous other peculiarities (which have been dealt with in Vol. X) for which 
reason we took them to be the representatives of an ancient lepidopteral type, whereas the Sphingidae are 
dependent on blossoms which belong to more modern creation. A drastic example of this dependency is offered 
to us by an Ethiopian Sphingid. The well-known explorer A. R. Wallace who had a particularly sharp eye 
for the biological relations in Nature was struck by the existence of the Madagassic orchid Angraecum sesqui- 
pedale being dependent on an insect provided with a proboscis of almost 10 in. length, which at that time 
(1891) was still unknown. Thirteen years later the predicted insect was discovered by Rothschild and Jordan 
in the Madagassic Sphingid Xanthopan morgani praedicta It. cb J. 
Many facts prove that the Sphingidae are a more modern lepidopteral class, having developed from 
the older element, the Saturnidae. As intermediate forms we may look upon the Brahmaeidae of the Old World 
and still more distinctly the corresponding Ceratocampidae of the New World. 
Being formations of modern creation, the Sphingidae also exhibit mimetic symptoms, though not only 
the vague tendency of copying indefinite models (as is the case with older lepidopteral families such as the 
Saturnidae in which eye-like spots by their sudden display have only a general bewildering effect, without 
copying individual parts of a beast of prey), but the Sphingidae present a most detailed kind of imitation of 
decidedly efficacious models, which is due to complicated (even structural) metamorphoses. The most striking 
cases are shown by the larvae. In the internally protected larvae as well as the inhabitants of the Euphorbia 
which contain poisonous milky juices we meet with the original primary form of the Sphingidae-bxr vae which 
are uniformly cylindrical with a small head and a horn-like tail, with a dorsal stripe and uniform lateral spots 
on the segments. According to circumstances, this shape is transformed into a protective form in all those 
Sphingidae that live on unpoisonous plants and are without any internal protection. In case of adaptation 
to an animal, the image of an eye is produced by that lateral spot which is situate at the place where the 
copied reptile would have its eye. i. e. on the side of the 4th ring. The lateral eyes of the other segments 
are then obliterated; this process is most obvious in the larva of Basiothia medea, where the imitated eye just 
begins to differentiate from the eye-spots of the other rings. The supernumerary eyes are then more and more 
obliterated in order not to impair the image of the snake. The develojnnent of the snake's eye is accompanied 
by the transformation of the anterior larval segments by acquiring the faculty of thickening the front portion 
of the insect into the shape of a snake’s head, which requires a specially adapted muscular apparatus. In order 
to copy still more strikingly the eye of the snake the eyespot of some species is even provided with an enamel 
gloss by means of a structural modification of the epidermis, so that the reflection of light, the sparkling of 
the vertebrate’s eye is likewise presented: such an insect is the larva of Theretra clotho or lucasi. Up to this 
accomplished imitation of the front portion of a snake we find all degrees of transition, and in some African 
Sphingid larvae we can even study the gradual progress of this metamorphosis. The beginning is exhibited 
e. g. in the larva of Theretra capensis, where we already notice, beside the greenish colour being adapted to 
that of the vine-leaves, the feebly developed eye-spot and the shrinkage of the horn-like tail which impairs 
the impression of the snake-image, and in the marking we see a transition from the leaf-design to the obliquely 
spotted marking of the dorsum of a snake. The momentum promoting the transformation is the inadequacy 
of the hitherto jirevailing degree of adaptation which does not prevent the insect from being pursued by butcher¬ 
birds (Fiscus collaris) and from being stuck on thorns. The dimorphism of very many Sphingid larvae likewise 
forms an illustration of this process of transformation from a protective resemblance to mimicry; many Sphin¬ 
gidae show forms which are either adapted green or mimetic brown, both of which may occur at the same time 
side by side, as for instance in the above mentioned Theretra capensis in South Africa, Hippotion osiris from 
Tropical Africa, in Herse convolvuli being distributed over the whole of Africa, as well as Acherontia atropos 
and other Ethiopian species. 
The reciprocal action between the colouring of the Sphingid larvae and their habits is distinctly 
disclosed in some genera whose larvae are well known to us, as for instance in the genus Celerio. C. nicaea, 
vespertilio, and hippophaes are very closely allied to each other, but they have very different larvae. The larva 
of nicaea is extremely variegated, white with red, black-edged eye-spots. But it lives on an Euphorbia which 
is so very poisonous that the inhabitants of Africa assert that some, young shoots of this spurge, when thrown 
into a brook, are sufficient to poison all the cattle drinking from it. The larva, filled up with these poisonous 
substances, is to be seen from afar sitting on the food-plant in the daytime, since it need not be afraid of 
any attacks by insectivorous animals. — The larva of vespertilio is also variegated, with red stripes and eyespots, 
hut it lives on unpoisonous Epilobium and therefore hides beneath stones at daybreak, often at a considerable 
distance from its food-plant; specimens which are sometimes met in daytime sitting on the food-plant, are 
mostly either stung or sick. — The third species of Celerio, hippophaes, lives on unpoisonous Hippophae 
rhamnoides (from the family of Elaeagnaceae); this larva is not variegated, but green and so exactly adapted 
to the food-plant that it is extremely difficult to identify it; it can therefore remain unnoticed on its food even 
in bright sunshine. 
