CATERPILLAR AND THE MOTH
the caterpillar, since the insect's brain occupies but a small part of the interior of the head (Fig. 154 , Br). From the lower edge of the triangular facial plate (Fig. ISZ, Clp) is suspended the broad, notched front lip, or labrum (Lin) that hangs as a protective flap over the bases of the jaws. At the sides of the labrum are the very small antennae (.4rit) of the caterpillar. On the lower part of each lateral hemisphere of the head are six small simple eyes, or ocelli (O), rive in an upper group, and one near the base of the antenna. With all its eyes, however, the caterpillar
Cr Vent Ht ?/v?al int Br..?Rect Phy ?-'??"?'??-???? ?- ? _ Mth / , ? ? ? ?oeGn? ?kG1 Fro. ?54- Diagrammatic lengthwise section of a caterpillar, showing the principal internal organs, except the tracheal system d?, anus; ?r, brain; C, crop; ?I, heart; I?I, ;ntestine; ?1?1, Malpighian tubule (two others are cut off near their bases); ?I?, mouth; Oe, oesophagus; pharynx; R«et, rectum; ??çl, silk gland; ?o«çn?, suboesophageal ganglion; stomach, or ventriculus; ??? ventral nerve cord appears to be very nearsighted and gives little evidence of being able to distinguish more than the presence or ab- sence of an object before it, or the difference between light and darkness. Those tent caterpillars that were starving on the denuded tree failed to perceive other food trees in full leaf only a few feet away. The general external form and structure of the tent caterpillar is shown at A of Figure 159. The body is soft and cylindrical. The head is a small, hard-walled capsule attached to the body by a short flexible neck. Back of the head and neck comes first a body region consisting of three segments that bear each a pair of small, jointed legs (L); and then comes a long region composed of ten segments supported on rive pairs of short, unjointed legs [ ?85 ]
INSECTS
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