THE SUGAR-CANE MOTH BORER. 



15 



Epipharyngeal shield (PL IV, fig. 6) (ES) not sharply defined, merging in a 

 broadly chitinized area on the central forward part of the labrum. Epipharyn- 

 geal setce (ET) triangularly grouped, well behind anterior margin of epipharynx, 

 moderately long, narrow, equidistant. Epipharyngeal rods (ER) indicated only 

 by their prominent posterior projections. 



Maxillulw normal. 



SPECIFIC DESCRIPTION. 



Summer form (PI. Ill, figs. 1, 3; PI. IV, fig. 2) : Head slightly trapezoidal in 

 outline viewed from above ; widest at the level of the posterior seta P 2 ; lateral 

 and frontal margins nearly straight; posterior region broad, not constricted; 

 ultraposterior setae of epicranium forming a very obtuse angle, with the apex of 

 the angle pointed to the longitudinal ridge (Lll) ; color rich brown, varying to 

 black at mouth parts and to orange on dorsal aspect. Prothoracic plate pale 

 brown, tinged with black ventrally. Body 

 white. Tubercles light brown or paler. 

 Abdominal tubercles II oval and about 

 twice as far apart as tubercles I. Setae 

 yellow to brown. Imaginary lines con- 

 necting setae I and II of abdominal seg- 

 ments 3, 4, and 5 (text fig. 3, a) on each 

 side, if prolonged, form angles averaging 

 30.2 degrees. Tubercle I on ninth ab- 

 dominal segment discernible. Spiracles 

 dark brown. Average length (10 speci- 

 mens) 25.6 mm. 



Winter form (PI. Ill, fig. 5) : Differs 

 from the summer form in the following 

 characters : Color yellow to rich brown, 

 varying to black at mouth parts and to 

 yellow on dorsal aspect. Prothoracic 

 plate yellow. Body tubercles white or 

 pale yellow and not easily distinguished 

 from ground color of body. Spiracles 

 dark brown, distinct and sharply con- 

 trasting with rest of body. Average 

 length (10 specimens) 22.4 mm. 



As the nearly related species Diatraea zeacolella is liable to con- 

 fusion with D. saccharalis crambidoides, Mr. Heinrich has furnished 

 the following descriptions : 



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■ -*!■ 



h 

 / l 



I o 



a 



Fig. 3. — a, Fourth abdominal segment, 

 dorsal view, of larva of sugar-cane 

 moth borer (Diatraea saccharalis cram- 

 bidoides), and diagram of angle formed 

 by imaginary line through bases of 

 setae ; b, same for larger corn stalk- 

 borer (Diatraea zeacolella). 



SPECIFIC DESCRIPTION OF LARVA OF DIATRAEA ZEACOLELLA. 



Summer form (PI. Ill, figs. 2, 4) : Head broadly oval, widest at the level of 

 posterior puncture P b ; the lateral and frontal margins slightly but evenly 

 rounded ; posterior region slightly constricted, narrower than middle of head ; 

 ultraposterior setae forming a very obtuse angle, with the apex of the angle 

 pointed to the lateral margin. (PI. IV, fig. 3.) Color yellow, varying to black 

 at mouth parts. Prothoracic plate yellow. Body white. Tubercles dark 

 brown, contrasting sharply with ground color of body. Abdominal tubercles II 

 narrowed and about four times as far apart as tubercles I. Setae yellow to 

 brown. Imaginary lines connecting setae I and II of abdominal segments 3, 4, 

 and 5 (text fig. 3, 6) on each side, if prolonged, form angles averaging 53.3 

 degrees. Tubercle I of ninth segment not discernible. Spiracles black. Aver- 

 age length (3 specimens) 25.2 mm. 



