THE EUROPEAN CORN BORER AND ITS CONTROL. 25 



i& and ii&. Seta iii is of medium length. On the dorsum of abdominal 

 segments 1 to 7, tubercles i and ii form a trapezoidal figure, while on the 

 dorsum of segment 8 they form a nearly rectangular figure. On the 

 dorsum of abdominal segment 9 is a large irregular-shaped, nearly oblong, 

 corneous tubercle bearing a long seta at ea^h of its posterior lateral angles, 

 and a distinct pmicture on the median anterior border. The nearly 

 elliptical preanal plate bears two short setae and one long seta along each 

 of the posterior lateral angles, and one short seta centrally located on 

 each side of the median line. Spiracles protruding, concolorous with 

 tubercles. 



Head black or dark brown, declivous and flattened in the newly hatched 

 larva, becoming more rounded as the larva develops. Adfrontal pieces 

 not perceptible in this or succeeding instars until the fifth. Clypeus pale 

 and distinct from frontal piece. Labrum pale, bilobate, with normal 

 arrangement of seta?. Mandibles reddish brown, not protruding. Ocelli 

 six in number, pale and protruding. Antennae with slight tinge of amber 

 on distal segments. 



Prothoracic shield averages .25 millimeter, slightly lighter in color 

 than the head, corneous, almost straight anteriorly, broadly rounded 

 posteriorly. Each half of the shield bears three setse on the anterior 

 border, two on the lateral posterior border, and one centrally located and 

 near the median line. Bases of setse surrounded by a black ring. A 

 perceptible indentation, but no division of shield along the middorsal 

 line. Venter of prothoracic segment appears darker owing to presence 

 of dark thoracic shield above. 



Thoracic legs, abdominal prolegs, preanal plate and anal prolegs amber. 

 Circle of crotchets on abdominal prolegs broken externally. Thoracic 

 feet and crotchets on abdommal and anal feet pale brown. Thoracic feet 

 corneous. 



Second Instar (see Plate I, Fig. 2). — Average measurements of 13 

 individuals, just molted: Length, 2.625 millimeters; head width, .46 

 millimeter. Length of head and prothoracic shield, one-sixth total 

 length of larva. Body subcjdindrical, amber-white to yellowish green 

 in color. Tubercles large, prominent, pale amber, polished; iv and v 

 present and coalescent on mesothorax and metathorax. Othei-wise the 

 arrangements of tubercles and setse are similar to preceding instar, and 

 remain fairly constant throughout the remaining larval stages. The 

 relative length of the longer body setae diminishes in each succeeding 

 instar. Spiracles pale amber at center, with black edges. Bases of 

 tubercles and setae surrounded by a black ring. 



Head deflexed. Clypeus pale and distinct from frontal piece. Labrum 

 pale brown. Mandibles reddish brown with black tips. Distal segments 

 of antennae pale amber, otherwise colorless. 



Prothoracic shield averages .414 millimeter wide or nearly equal to 

 that of head. Indentation along middorsal line more pronounced but 

 no division. Venter of prothoracic segment darker. 



