14 ILLINOIS BIOLOGICAL MONOGRAPHS [246 



tuberant than in the Coccinellini, the flagellum is more mound-like, and 

 one of the three apical setae is much larger than the other two. Scymnus 

 (Fig. 39) presents a type of antennae that shows a wide variation from the 

 type found in the other genera of the family. The antenna of this genus 

 is wider than long, only slightly chitinized, scarcely elevated, and conical. 

 The antacoria (Fig. 39, ante) is narrow; the scape (Fig. 39, sc) is about three 

 times as wide as long; the pedicel (Fig. 39, pd) is about twice as wide as 

 long, its distal end much narrower than the proximal; and the flagellum 

 (Fig. 39, fl) is more or less mound-like and about twice as wide as long. 



All of the coccinellid larvae examined have well-developed mandibles. 

 They may be of a crushing type, that is with many dentes as in Epilachna, 

 or they may be of a piercing type, that is with one or two dentes as in all 

 of the members of the subfamily Coccinellinae. Within the family there 

 are all stages of variation between these two extremes. The type of man- 

 dible found in such generalized genera as Periplaneta or Corydalis is that 

 with many dentes. This tends to show that in these forms the mandible 

 is a crushing organ primarily and not for piercing as appears to be the case 

 in the specialized coccinellid larvae. 



The mandible of C. bivulnerus (Figs. 40, 41) is of moderate size, heavily 

 chitinized, somewhat triangular in outline, thick and heavy at the proximal 

 end, and tapering to a bidentate distal point. The proximo-mesal margin 

 of each mandible is provided with a distinct wedge-shaped mola (Fig. 41, 

 mo) and the proximo-lateral margin with a stout spine-like seta. On the 

 cephalo-mesal margin of each there is a preartis (Figs. 42, 41, ps) which 

 articulates in a precoila (Fig. 5, pel); on the caudo-mesal margin there is 

 a postartis (Fig. 41, poa) which articulates in a postcoila. The mandibles 

 of Chilocorus are intermediate in form between the two extreme types. 

 The majority of the species studied have mandibles similar to those of 

 Chilocorus and tend to show an evolution from the multidentate type 

 found in Epilachna, which are entirely phytophagous, to the unidentate 

 type found in Hyperaspis, Microweisea, and Scymnus, which are entirely 

 carnivorous. In all of the genera studied the mola is present, but it is 

 much reduced, is almost indistinguishable in Epilachna (Fig. 42, mo) and 

 shows the extreme condition of its reduction in Microweisea. The mandi- 

 bles of all coccinellid larvae are connected with the head capsule cephalad 

 and ventrad of the antennal fossae by a small and distinct membrane. 

 This membrane is the mandacoria (Fig. 5, mco). The extensor muscles 

 are attached to the lateral margin of the mandible between the preartis 

 and the postartis, while the retractor muscles are attached near the mesal 

 portion of the mandible. 



The maxillae of the Coccinellidae show a greater degree of departure 

 from the primitive type than any other of the movable parts. They 

 resemble in general form the maxillae of Periplaneta and the larvae of 



