32 ILLINOIS BIOLOGICAL MONOGRAPHS [264 



Chilocorini 



The body is subovate, widest at the metathorax. The first three 

 abdominal segments are slightly narrower than the metathorax, segments 

 four to eight are successively narrower, segment nine is about as wide as 

 long, its caudal margin is broadly rounded and its lateral margin is pro- 

 vided with a distinct struma; and segment ten is small and directed ven- 

 trad. The dorsal and lateral aspects of the body are provided with long 

 senti the length of which varies on the different portions. The epicranial 

 stem and epicranial arms are present. The epicranial stem extends about 

 one-third of the distance from the occipital foramen to a line drawn through 

 the antacoriae, divides and forms the two epicranial arms which diverge 

 gradually for a short distance, then widely, and finally each extends 

 laterad to a point dorsad of an antacoria and ventrad of an ocellus where 

 it becomes obsolete. The mandibles are triangular in outline, heavily 

 chitinized, the apex is bifurcated, and the proximo-mesal margin is pro- 

 vided with a distinct mola. 



This tribe is represented in the material studied by the single genus 

 Chilocorus Leach. 



Chilocorus bivulnerus Muls. — The head is chitinized, dark, and pro- 

 vided with numerous setae. The epicranial stem and epicranial arms are 

 distinct; the clypeal suture is indicated on each lateral margin of the head. 

 The mouth is directed cephalo-ventrad. The prothorax is provided with 

 a large dark colored dorsal shield bearing ten senti, six of which are ar- 

 ranged in a transverse row near the cephalic margin. The lateral aspect 

 of the prothorax bears a small group of setae cephalo-dorsad of the pro- 

 coxacoria. The cephalic portion of the prosternum also bears a small 

 group of setae on each side of the meson. The procoxacoriae are distant. 

 The mesotergum is distinctly longer and narrower than the metatergum. 

 Each is provided with four large senti arranged in a transverse row; the 

 dorsal senti are distinctly smaller than the lateral ones. The pinacula are 

 small and bear distinct setae. The mesopleural area is longer than the 

 metapleural; both areas are obliquely crossed by a distinct furrow. The 

 cephalic portions of the mesopleural and metapleural areas are subequal 

 in size, triangular, and each provided with a large sentus. The meso- 

 thoracic spiracle is located in the mesocoria near the cephalic margin of the 

 mesothoracic sentus; the metathoracic spiracle is rudimentary or wanting. 

 The caudal portions of the mesopleural and metapleural areas are unequal 

 in size, that of the metapleural area is much larger than that of the meso- 

 pleural. The cephalic metapleural sentus is about one-half as long as the 

 caudal one. The mesosternum and metasternum are similar in size and 

 shape. The mesocoria is distinct while the metacoria is obscure. The 

 cephalic portions of the mesosternum and metasternum are each provided 

 with a chalaza on each side of the ventro-meson; these chalazae are sur- 



