30 ILLINOIS BIOLOGICAL MONOGRAPHS [262 



by two or three large pubescent species belonging to the single genus 

 Epilachna." One species occurs in small numbers in southern Illinois. 

 The Epilachninae are truly phytophagous. Our common species feeds 

 almost entirely upon the squash plant and its relatives. The beetle is 

 commonly called the squash lady-bug. This subfamily is represented in 

 the material studied by a single species of the genus Epilachna Chevrolat. 

 Epilachna borealis Fab. — The prothorax is slightly chitinized with a 

 transverse row of four scoli on the dorsum near its cephalic margin and a 

 transverse row of small setae on its caudal margin; the pleural area is small 

 and glabrous; the prosternum is short with two distinct setae on the 

 ventro-meson; and the procoxacoriae are distant. The mesothorax and 

 metathorax are subequal in length and width, the dorsum of each with 

 four scoli, two on each side of the meson arising from the same pinaculum; 

 the mesothoracic spiracles are located in the mesocoria; the metathoracic 

 spiracles are wanting; the caudal portion of the mesothoracic and meta- 

 thoracic pleural areas are each provided with a large prominent scolus; 

 the mesothoracic and metathoracic sterna are each provided with a group 

 of setae on each side of the ventro-meson; and the mesocoxacoriae and 

 metacoxacoriae are distant. The coxa is short and subcylindrical; the 

 trochanter is triangular, about as long as the coxa and bears a few setae; 

 the femur is as wide as the trochanter, about twice as long and covered 

 with numerous small stiff setae; the tibia is about as long as the femur and 

 about two-thirds as wide, its dorsal and lateral surfaces are covered with 

 short stiff setae, its ventral surface is thickly covered with fine setae, and 

 the distal one-third is covered with tenent hairs; and the tarsus consists 

 of a single segment which bears the heavily chitinized hooked claw and 

 a few tenent hairs. The terga of the abdominal segments one to eight 

 inclusive are similar. Each tergum is provided with four scoli, the dorsal 

 scoli are adjacent to each other and the meson and the dorso-lateral scoli 

 are on the lateral margins of the tergum. The ninth tergum bears four 

 strumae which represent the dorsal and dorso-lateral groups; the tenth 

 segment is membraneous. Each lateral aspect of segments one to six is 

 provided with a prominent lateral scolus, of segments seven and eight with 

 a lateral struma, and of segment nine with a lateral verruca. The para- 

 lateral group is represented by a prominent chalaza surrounded by a group 

 of small setae ventrad of each lateral scolus. Sternum one is provided 

 with two prominent ventral chalazae, the ventrolaterals are wanting; 

 sterna two to nine bear two adjacent ventral chalazae and two ventro- 

 lateral chalazae located near the lateral portion of each sternum; and 

 sternum ten is crescent-shaped and armed with setae. The rectum is 

 evaginated to form a disk-like sucker. It is used as an aid in locomotion. 



