[a]Fig. 12.]—Caterpillar of Papilio philenor (Riley).
[a]Fig. 13.]—Head of caterpillar of Papilio asterias, front view, enlarged.
[a]Fig. 14.]—Head of caterpillar of Anosia plexippus, lower side, magnified 10 diameters: lb, labrum, or upper lip; md, mandibles; mx, maxilla, with two palpi; lm, labium, or lower lip, with one pair of palpi; s, spinneret; a, antenna; o, ocelli. (After Burgess.)
The head is always conspicuous, composed of horny or chitinous material, but varying exceedingly in form and size. It is very rarely small and retracted. It is generally large, hemispherical, conical, or bilobed. In some families it is ornamented by horn-like projections. On the lower side are the mouth-parts, consisting of the upper lip, the mandibles, the antennæ, or feelers, the under lip, the maxillæ, and two sets of palpi, known as the maxillary and the labial palpi. In many genera the labium, or under lip, is provided with a short, horny projection known as the spinneret, through which the silk secreted by the caterpillar is passed. On either side, just above the mandibles, are located the eyes, or ocelli, which in the caterpillar are simple, round, shining prominences, generally only to be clearly distinguished by the aid of a magnifying-glass. These ocelli are frequently arranged in series on each side. The palpi are organs of touch connected with the maxillæ and the labium, or under lip, and are used in the process of feeding, and also when the caterpillar is crawling about from place to place. The larva appears to guide itself in great part by means of the palpi.
[a]Fig. 15.]—Head of caterpillar of Anosia plexippus, side view, showing ocelli.