241] THE LARVAE OF THE COCCI NELLI DAE— GAGE 



MORPHOLOGY 



This discussion of the general comparative morphology of coccinellid 

 larvae is based for the most part upon a study of Chilocorus bivulnerus. 

 This species represents the most generalized condition of the carnivorous 

 coccinellids that I have studied. A still more generalized condition occurs, 

 however, in the subfamily Epilachninae, the members of which are for 

 the most part entirely phytophagous. 



HEAD 



The heads of coccinellid larvae are symmetrical and the general outline 

 is circular or nearly so, except in the genus Microweisea in which it is oval 

 or oblong. In Chilocorus and Epilachna the mouth is directed ventrad; 

 while in all of the genera of the Coccinellini, Hyperaspini, and Microweis- 

 eini it is directed caudo-ventrad. The greatest departure from the gen- 

 eralized condition is found in Scymnus. In this genus the mouth is directed 

 cephalad. For the sake of convenience the head will be considered under 

 two divisions; first, the fixed parts; second, the movable parts. 



Fixed Parts of the Head 



The fixed parts of the head consist of an external and an internal 

 skeleton. The external skeleton is composed of the fused front and post- 

 clypeus, preclypeus, veterx, labrum, and gula. The boundaries of these 

 sclerites are marked by distinct furrows or sutures. The internal skeleton 

 is made up of the floor-like tentorium, which in the Coccinellidae consists 

 of three parts. 



In the head capsule of C. bivulnerus the epicranial suture (Fig. 6, es) 

 is present on the meson. It extends from the occipital foramen (Fig. 17, 

 of) to a point on the cephalic aspect about one-third the distance from the 

 occipital foramen to a line drawn through the antennal fossae. This part 

 of the epicranial suture is the epicranial stem (Fig. 6, es). The epicranial 

 stem bifurcates at its ventral end and the two epicranial arms (Fig. 6, ea) 

 extend latero-ventrad a short distance, then make a broad curve and 

 extend ventro-mesad on each side to a point where they become much 

 thickened. Each thickening is a pretentorina (Fig. 6, pt) and marks the 

 point of invagination of the pretentorium. The epicranial arms curve 

 broadly laterad and ventrad from each pretentorina to a point dorso- 

 mesad of an antennal fossa where they become obsolete. The three 

 sclerites included within or ventrad of the fork of the epicranial stem are 

 the fused front and postclypeus (Fig. 6, fc) and the labrum (Fig. 6, I). 

 There is an indistinct furrow which marks the position of the clypeal 



