THE MAIZE BILLBUG. 17 



curved, swelling ventralfy from the third abdominal joint posteriorly, slightly 

 recurved and rounded at anal extremity. Head large, oblong, obtusely angulate 

 at base, sinuately narrowed anteriorly ; frontal margin with a shallow einargina- 

 tion between the mandibles ; upper surface with a median channel, the occipital 

 portion deeply incised, with raised edges, continuing as a shallow impressed line 

 to the middle of the front ; on either side an engraved line, commencing upon 

 the vertex, becoming deeper after crossing the branches of the Y suture, and 

 terminating at the frontal margin in a bristle-bearing depression ; sides and 

 vertex with several long bristles arising in depressions ; antennae rudimentary, 

 occupying minute pits on the frontal margin at the middle of the base of man- 

 dibles ; ocelli a single pair, visible only as translucent spots upon the anterior 

 face of the thickened frontal margin, outside of and closely contiguous to the 

 antennae from which they are separated by the branches of the Y suture, a few 

 pigment cells obscurely visible beneath the surface ; clypeus free, transverse, 

 trapezoidal, with faint impressions along the base and at the sides ; labrum 

 small, elliptical, bearing spines and bristles, a furrow each side of the middle, 

 forming three ridges, so that the organ, when deflected, appears three-lobed ; 

 mandibles stout, triangular, unarmed, with an obsolete longitudinal furrow on 

 the outer face ; maxilla? stout, cardinal piece transverse, basal piece elongate, 

 bearing a palpus of two short joints, and a small rounded lobe, furnished at tip 

 with a brush of spiny hairs, the lobe concealed by the labium ; labium consist- 

 ing of a large triangular mentum, excavate beneath, and a hastate palpiger, 

 with a deep median channel ; labial palpi divergent, separated by the ligula, 

 of two joints subequal in length ; ligula represented by a prominent rounded 

 lobe, densely ciliate on the under surface. Thoracic joints separated above by 

 transverse folds ; the first wider, covered above by a transverse, thinly chitinous 

 plate ; the two following similar to the abdominal joints ; abdominal joints 

 forming on the dorsum narrow transverse folds, separated by two wider folds, 

 the anterior fold attaining the ventral surface, the second fold confined to the 

 dorsum, eighth and ninth abdominal joints longer, excavate above, without 

 dorsal folds ; beneath, the first three joints contracted, the succeeding joints 

 enlarged, the terminal joint broadly rounded, with anal opening upon a fold at 

 its base ; sides of each joint presenting numerous longitudinal folds ; stigmata 

 very large, nine pairs ; the first on the anterior margin of the prothorax, low 

 down upon the sides ; the remainder upon the sides of the first eight abdominal 

 joints, above the lateral prominences, beginning upon the first joint at the 

 middle of the side and gradually rising to a dorsal position upon the eighth 

 joint; thoracic and last abdominal pairs large, oval; the intermediate pairs 

 smaller, elliptical ; all with chitinous margins of dark-brown color. The notice- 

 able features of this larva are its cephalic vittae, and conspicuous spiracles. 



Upon issuing from the eggshell the young larvae are about 5 mm. 

 long and 2 mm. thick. They at once begin feeding on the tissues of 

 the young corn at the bottom of the egg puncture (fig. 7, &), direct- 

 ing their burrowing inward and downward into the taproot. When 

 they finish eating the tender parts of the taproot they direct their 

 feeding upward, continuing until full grown, allowing the lower 

 portion of the burrow to catch the frass and excrement (fig. 7, a). 

 This burrowing of the taproot of the young growing corn plant is 

 disastrous to the root system (PL I, figs. 1, 2) ; the roots, first dying 

 at the tips, soon become of little use to the plant, allowing it to die 

 or to become more or less dwarfed (PL II). The corn plants shown 



