THE LESSER CORN STALK-BORER. 



9 



the shorter. Anal plate somewhat triangular, dusky. Body pale yellowish to yel- 

 lowish green; posterior portion of each segment bright red to reddish brown on dor- 

 sum; whole dorsum of joint 5 of this color. These areas are joined by faint stripes, 

 some little distance apart, of the same color, giving the larva a longitudinally striped 

 as well as transversely banded appearance. Segments all slightly swollen, except 

 last. Tubercles small; "iv-v" coalescent on joints 5-13, inclusive, below spiracle 

 on joint 5, laterad and slightly cephalad of spiracle on joints 6-12, inclusive, directly 

 laterad of " iii " in joint 13. Setse " iib " of joint 3 and " iii " of joint 12 0.25 mm. long, 

 about twice as long as others. Abdominal segments except terminal crossed trans- 

 versely through the middle by shallow grooves on dorsum. Thoracic feet pale, 

 though somewhat dusky; abdominal prolegs all whitish. 



Second instar.— Length 2.7 mm. Head slightly bilobed, flattened, highly polished, 

 blackish brown, width 0.29 mm. , clypeus 0.14 mm. high. Cervical shield concolorous 

 with head, 0.26 mm. in width. Anal plate dusky. Body pale yellowish; transverse 

 bands and stripes adjoining as in preceding stage. Tubercles "iib" of joint 3 and 

 "iii" of joint 12 large, each supplied with a long seta as before ; 

 subprimaries present. Thoracic feet pale to dusky; abdom- 

 inal prolegs same as venter of body, pale yellowish. 



Third instar. — Length 5.7 mm. Head as in second instar 

 except trifle paler, width 0.44 mm., a little wider than high; 

 clypeus 0.20 mm. high; labrum pale amber, mandibles dark 

 amber, almost black at tips; antennae pale amber at tips, 

 otherwise pale whitish. Cervical shield large, darker than 

 head, the anterior border extending somewhat over the head 

 lobes, wider than head, width 0.54 mm., length 0.30 mm., 

 corneous, polished. Body pale greenish white to pale yel- 

 lowish green; transverse bands and connecting stripes reddish 

 brown to brown, sometimes only greenish white between the 

 stripes; tapering posteriorly. Thoracic legs dusky; abdominal 

 prolegs pale yellowish green, same as venter. 



Fourth instar. — Length 6.9 mm. Head slightly bilobed, 

 polished dark brown, 0.61 mm., about two-thirds as high as 

 wide; clypeus 0.25 mm. high; around base of spines pale. 

 Cervical shield concolorous with head, width 0.89 mm., length 

 0.45 mm. Prespiracular tubercle large, somewhat corneous, 

 dusky; sub ventrical tubercle also dusky, normal. Body as 

 in preceding stage except that venter is taking on deep green 

 color; greenish white more conspicuous and breaking into the 

 transverse bands, very deeply in some segments; stripes joining transverse bands 

 wider than before. Thoracic legs and abdominal prolegs as before. 



Fifth instar. — Length 8.8 mm. Head bilobed and polished as before, very dark 

 brown black, width 0.89 mm., clypeus 0.32 mm. high, the paraclypeal pieces distinct, 

 the sutures almost touching the beginning of the intersection point of the lobes on the 

 vertex, whitish; labrum pale amber, mandibles amber, very dark at tips. Cervical 

 shield darker than head, 1.02 mm. wide, 0.62 mm. long; on the meson is a pale stripe 

 extending longitudinally from the posterior border to a point almost across the shield. 

 Body as in preceding stage except that transverse bands are now at a point of being 

 broken up, giving way to pale yellowish white color of the dorsum, the dark color being 

 now confined chiefly to the longitudinal stripes, now almost continuous over the body 

 but very irregular; in some specimens there is a whitish patch, ellipsoidal in outline, 

 on the dorsum of joints 3 and 4; venter tinged with pale reddish. Thoracic legs and 

 abdominal prolegs as in preceding stage. 



Sixth instar. — Length 16.2 mm. (fig. 3) . Head slightly bilobed, somewhat flattened, 

 dark brownish black, highly polished, width 1.11 mm. Clypeus triangular, somewhat 

 83986°— Bull. 539—17 2 



Fig. 3.— The lesser corn 

 stalk-borer: Larva. 

 Greatly enlarged. (Orig- 

 inal.) 



