NO. 6 



CATERPILLAR AND BUTTERFLY — SNODGRASS 



cavity and that there is no pharyngeal dilatation. All Lepidoptera that 

 feed in the adult stage, however, are provided with a sucking pump 

 in the head connected with the base of the proboscis and continuous 

 into the oesophagus. In a comparative study of the pump, Schmitt 

 (1938) shows that the organ varies somewhat in size and structure in 

 different species, but is always operated by two sets of dilator muscles 

 separated by the frontal ganglion and its brain connectives. The 

 preganglion muscles arise on the clypeal region of the head, the post- 



Fig. 4. — Alimentary canal of adult moths. 



A, Malacosoma americanum. B, Sanninoidea exitiosa. 

 alnt, anterior intestine; Mai, Malpighian tubules (not shown full length); 

 Oe, oesophagus ; Red, rectum ; Vent, ventriculus ; Ves, oesophageal vesicle. 



ganglion muscles on the frontal region. The lepidopterous food pump, 

 therefore, is a combination of the preoral cibarium and the postoral 

 pharynx. The same type of pump is described by Srivastava (1957) 

 in Papilio demolcus, and is strongly developed in the sphinx moth 

 (fig. 3 F, Pmp). Its principal dilator muscles (3,4,5) arise on the 

 frons (Fr) and are therefore pharyngeal, the anterior muscles (1,2) 

 arising on the clypeal region (Clp) are cibarial. The sucking pump 

 of the honey bee is also cibario-pharyngeal, but in most sucking insects 

 the pump is entirely cibarial. 



In contrast to the highly developed sucking apparatus, the alimen- 

 tary canal of adult Lepidoptera is much simplified, as might be ex- 

 pected of a nectar- feeding insect. In the moth of the tent caterpillar 

 (fig. 4 A), for example, the oesophagus (Oe) is a long slender tube 



