NO. II LARVAE OF THE ELATERID BEETLES — GLEN 97 



of the dorsal plate of the ninth abdominal segment, and without 

 punctures in the region between the caudal notch and the pleural area 

 of the ninth abdominal segment. 



The largest larva examined was 14 mm. long and 2.5 mm. broad, 

 but undoubtedly it was immature. Dorsum dark brown, eighth ab- 

 dominal segment not darker than preceding segments. Each medio- 

 tergite on second to eighth abdominal segments with a posterior trans- 

 verse row of 5 to 7 setae (8 to 15 setae in similar location in "western 

 species"). 



Urogomphi (fig. 21, /) resemble those of "western species," but 

 inner prongs relatively larger ; outer prongs usually narrower at tips ; 

 and somewhat greater angle between prongs of each urogomphus. 



"Western species." — Van Dyke (1932, p. 428) states that the sub- 

 species nigricans (Fall) ranges throughout western Washington and 

 Oregon and south along the high Sierra Nevada whereas the other 

 western subspecies, diversicolor (Eschscholtz), is a lowland form that 

 breeds in the rotting parts of old living oaks. Larvae used in the 

 present study were taken from bull pine (Pinus ponderosa) and 

 Douglas fir (Pseudotsuga mucronata) in Oregon and California. 



This larva (fig. 21, b) is readily identified by its very dark brown 

 color, great abundance of setae, and the characteristic urogomphi (ur, 

 fig. 21, g, h). 



Description of "mature" larva of "western species." — Length 22 

 mm. ; greatest breadth 3.5 mm. on fourth abdominal segment. A fully 

 distended larva measured 24 mm. Body robust; convex dorsally, 

 flatter ventrally; abundantly provided with setae; with large mem- 

 branes on lateral aspect; all segments broader than long; head and 

 ninth abdominal segment about two-thirds greatest body width. 

 Dorsum dark brown, sometimes approaching black brown; head, 

 prothorax, and eighth and ninth abdominal segments usually very 

 dark; on abdominal segments pigmentation is stronger posterior to 

 imaginary line joining transverse branches of impressions on medio- 

 tergites; venter pale yellow to creamy white, darker on ventral sur- 

 face of head and terminal part of ninth abdominal segment. Dorsum 

 slightly rugose, moderately to densely punctate, punctures small except 

 on ninth abdominal segment. 



Head (fig. 21, a) subquadrangular with slightly arcuate sides; not 

 as thick at base as long ; flattened above and below. 



Frontoclypeal region extending backward to or almost to foramen 

 magnum, bluntly rounded posteriorly. Two prominent anterior naso- 

 sulcal setae on each side of base of nasale. Nasale unidentate, termi- 

 nating sharply when uneroded. Subnasale consisting of transverse 



