259] NOCTUID LARVAE— RIPLEY 17 



being formed so that the denies of one fit into the emarginations of the 

 other. Each mandible bears two large primary setae on its lateral aspect. 



The great majority of caterpillars present no striking variation in the 

 maxillae, although a few exceptional conditions have been recorded. 

 Tragardh has discussed certain modifications found in those of the leaf- 

 miners. Packard's figures of the larval mouth-parts of Eriocephala repre- 

 sent three free segments of the maxillary palpus instead of the two found 

 in all families other than the Micropterygidae. Differences exist in the 

 relative size of the segments in various families, as shown by the figures 

 of Forbes. The noctuid larval maxilla (Figs. 24-25) is typical for the 

 order, presenting the highly specialized condition found in that of all 

 caterpillars. 



The labium of lepidopterous larvae exhibits a degree of specialization 

 unequalled even by the maxillae. The homologizing of its parts con- 

 sequently presents a difficult problem. Its condition in the Noctuidae 

 appears to be fairly typical for the order, although certain types of spin- 

 neret frequently occur within the family which are not generally found in 

 caterpillars. The labium lies between the two maxillae, its proximal two- 

 thirds being joined on each side to the cardo and stipes by a labacoria, 

 which has been reduced in width to a mere suture. The submentum is 

 large, as it is in the larvae of other orders, and is for the most part usually 

 membranous or slightly chitinized. It is broadly attached to the ventral 

 margin of the postgenae for the entire width of its proximal end by a 

 narrow strip of membrane. This specialized condition has been brought 

 about by the extension mesad of the postgenae, so that they separate the 

 labium from the cervix, which typically bears this appendage in insects. 

 The narrow strip of membrane which connects the postgenae and the 

 submentum is evidently a portion of the cervacoria, which has become 

 separated from the rest by the unusual development of these sclerites. 

 The mesal portion of the submentum is occasionally not borne by the 

 postgenae, since in many species they do not extend to the meson. A 

 subtriangular sclerite located in each latero-proximal corner of the labium is 

 of very frequent occurrence throughout the order and is apparently always 

 present in the Noctuidae. Berlese does not figure these in his drawing of the 

 mouth-parts of Acherontia, evidently considering them as secondary, if 

 they occur in this species. Dampf refers to them as postmentalstiicke, a 

 term previously employed by Verhoeff, also regarding them as secondary, 

 while Forbes, on the other hand, believed them to constitute the sub- 

 mentum, although they are not represented in several of his figures of the 

 labia of caterpillars. The interpretation of the latter investigator leads 

 him to consider as mentum the large membranous region regarded as 

 submentum by Berlese, Dampf, and the author. The corresponding 

 region in the coccinellid larvae is referred to as submentum by Gage and 



