Fig. 188—Larvae of Hammock-moth, Perophora sanguinolenta, projecting from their Hammocks, built from their own excrement. South America. (After Jones.)
The Argentinian Insect Mamillo curtisea[[256]] is also probably an ally of Lacosoma. The caterpillar of this moth spins a dwelling for itself, and is remarkable from the bright colour of the thoracic segments, the following somites being colourless; the head bears a pair of large processes, quite different from those figured by Harris. The moth itself is very Geometrid-like in colour and form. This species is now assigned to Perophora, but it seems to be very doubtful whether many of the species placed in this genus really belong to it. The diversity of habits and instincts evinced by these moths of exceptional modes of life, but considered to be closely allied, is very interesting. The most remarkable of all is the Hammock-moth, Perophora sanguinolenta, of the centre of South America, the larva of which constructs its portable habitations out of its own excrement, which is of peculiar form, specially suitable for the purpose. The caterpillar, when wishing to enlarge its case, builds it up from excrement "flattened at the sides, so as to adapt it for building purposes."[[257]]
Fig. 189.—Antennae of Sphingidae. A, One joint of antenna of Choerocampa elpenor ♂, enlarged; B, three joints of antenna of Sphinx ligustri, seen from one side, and enlarged.
Fam. 9. Sphingidae (Hawk-moths).—A very important family of moths of large or moderate size. They have a proboscis which is frequently very long; there is a frenulum; the body is stouter than in most other Lepidoptera, and the wings are of small superficies in comparison with it; the antennae are somewhat peculiar, having a thick, solid appearance, pointed at the tip. This is usually somewhat hooked, and bears a few hairs. In the males the antennae are formed in a manner specially characteristic of the family. In section, each joint shows a chitinous process on the under side (Fig. 189, A), forming with that of the other joints a continuous ridge, and on each side of this ridge there exists a series of short, delicate "cilia" arranged in a very beautiful manner (Fig. 189, B). This structure, with some modifications, appears to be usually present in the family; it attains a very perfect development in cases where the tips of two rows of cilia bend towards one another, meeting so as to form an arched cavity. This structure is different from what occurs in the males of other families of Lepidoptera, for though cilia are very common, they are usually placed either on two projections from the body of the antennae (instead of on the two sides of a single projection), or there is but a single whorl, or set, of them on each joint (Catocala, etc.). The front wings are usually pointed at the tip, and are long in proportion to their width; but in the Smerinthini they are of different form, with the outer margin scalloped; the hind wings are remarkably small; the abdomen is frequently pointed, but in the Macroglossini, or Humming-bird hawk-moths, it is furnished at the tip with a tuft, or with two tufts, of dense, long scales, capable of expansion.
The larvae are remarkable for their colours and form. The anterior segments are attenuated, but are capable of great retraction, so that in repose (Fig. 190, A) this shape is concealed by the curious attitudes that are assumed. There is in nearly all cases a conspicuous horn on the eleventh segment, and the body at the extremity behind the horn is so much modified that the terminal two segments look like little more than a pair of large claspers. In the Choerocampini, the thoracic segments are retractile, and can be withdrawn into the more or less inflated fourth segment, and give the creature somewhat the appearance of a miniature hooded snake. The larvae of Sphingidae do not bear any conspicuous hairs—except during the first instar. They do not spin cocoons, but bury themselves in the earth. The pupa is remarkable from the deep cleft that exists to admit air to the first spiracle, and for a deep depression on each side of the anterior part of abdominal segments 5-7; in some cases the proboscis projects on the breast somewhat like the handle of a pitcher.
Fig. 190—Larva of the Poplar Hawk-moth, Smerinthus populi. × 1. A, in repose; B, in movement.
A great deal has been written on the colours, markings, and attitudes of Sphingid larvae, and many interesting facts have been brought to light. We may refer the reader to the writings of Weismann[[258]] and Poulton,[[259]] without, however, recommending him to place an implicit confidence in their somewhat metaphysical disquisitions; for the views there shadowed will necessarily became much modified with the advance of exact knowledge. It is certain that the position assumed by the same individual varies much according to age, and to the interval since the last moult; sometimes the attitude is much more remarkable than that shown in Figure 190, A, for the anterior segments are held erect, as well as contracted, the front part of the body being curled, and the Insect supported by the claspers and two pairs only of the abdominal feet. There is, too, a considerable difference in colour before and after an ecdysis. Piepers, who has had a long experience among Sphingid larvae in Java, considers that much of what has been written as to the protective value of their colours and attitudes, is mere fancy, and wild generalisation.[[260]]
Sphingidae have been recorded as capable of producing sounds in the larval and pupal, as well as in the perfect, instars; but the method in which this is done has not been ascertained, except in the case of the imago of the Death's-head moth, which is well known to emit a very audible cry when not on the wing; in this case it is highly probable that the method is the friction of the palpi against the proboscis, as stated by Réaumur and Landois; the inner face of the palp is said to be marked in this case with fine ridges or striae.