FORM, GROWTH, AND CHANGE 57 



group of three or four simple eyes (ocelli) on either side, while 

 the feeler (At) is short, consisting of only three segments each 

 nearly as broad as long. A most striking divergence from the 

 adult shown by the larva, is the presence of a pair of strong 

 biting mandibles (Mn), essentially like those of a grasshopper 

 or dragon-fly, for the caterpillar, unlike its parents, swallows 

 solid food consisting of leaves or other plant-tissues which it 

 bites off and devours. The maxillae (Mx) are curiously 

 simple, each consisting of a two-segmented base which 



Mn 



FIG. 31. 



A, Head of a Moth, showing sucking trunk formed by flexible maxillary galeae (g) between labial 

 palps (p) ; c, face ; e, eye ; I, labrum ; m, doubtful vestigial mandible. B, Basal part of maxilla 

 (6) removed from head ; p, vestigial palp. Magnified. C, Head of goat-moth Caterpillar (Cossus) 

 seen from behind ; At, feeler ; Mn, mandible ; MX, maxilla ; Lm, labium with spinneret pro- 

 jecting beyond it. From Carpenter, " Life Story of Insects " (C. after Lyonet). 



carries a short bristle-bearing palp and outer and inner lobes, 

 corresponding apparently to the typical galea and lacinia. 

 Between the maxillae is situated the labium (Lm), which has a 

 large basal plate (mentum) bearing a pair of small palps. Just 

 in front of the labium within the mouth is a conical chitinous 

 process usually regarded as an outgrowth of the tongue 

 (hypopharynx). This is the caterpillar's spinneret (Fig. 32), 

 for at its tip there opens the duct leading from the silk-glands 

 most important and characteristic larval organs, as they 

 produce a sticky fluid which, hardening on exposure to the 



