ANATOMY AND PHYSIOLOGY 



33 



FIG. 51. Head of a sphingid moth, Phlege- 

 thontins sexta. a, antenna; c, clypeus; e, eye; 

 /, labrum; m, mandible; p, pilifer; pr, pro- 

 boscis. 



Lepidoptera. In Lepidoptera, excepting Eriocephala, the labrum is 



reduced (Fig. 51) and the mandibles are either rudimentary or absent 



(Rhopalocera) . The two maxillae 



are represented by their galeae, 



which form a conspicuous pro- 

 boscis; the grooved inner faces 



of the galeae (or laciniae, according 



to Kellogg) form the sucking tube, 



which opens into the oesophagus. 



The labium is reduced, though 



the labial palpi (Fig. 52) are well 



developed. The so-called rudi- 

 mentary mandibles of Anosia and 



other forms have been shown by 



Kellogg to be lateral projections 



of the labrum (Fig. 51) and he 



terms them pilifer s. 



The exceptional structure of 



the mouth parts in the generalized genus Eriocephala (Micropteryx) sheds 



much light on the morphology of these organs 

 in other Lepidoptera, as Walter and Kellogg 

 have shown. In this genus there are func- 

 tional mandibles; the maxilla presents palpus, 

 galea, lacinia, stipes and cardo, though there 

 is no proboscis; the labium has well developed 

 submentum, mentum and palpi; a hypo- 

 pharynx is present. 



The sucking apparatus, as described by 

 Burgess, is essentially like that of Diptera. 

 Five muscles, originating at the skull and' in- 

 serted on the wall of a pharyngeal bulb, serve 

 to dilate the bulb that it may suck in fluids, 

 while numerous circular muscles serve by con- 

 tracting successively to squeeze the contents 

 of the bulb back into the stomach; a hypo- 

 pharyngeal valve prevents their return forward. 

 Diptera. In the female mosquito the 

 mouth parts (Fig. 53) are long and slender. 



As Dimmock has found, the labrum and epipharynx combine 1 to form a 



1 Kulagin, however, describes them as remaining separate. 



4 



FIG. 52. Head of a but- 

 terfly, Vanessa, a, antennae; 

 /, labial palpus; p, proboscis. 



