NO. II LARVAE OF THE ELATERID BEETLES GLEN 167 



Genus ELATHOUS Reitter 



ELATHOUS BICOLOR (LeConte) 



Figures ii, c; 2)Z, a, b 



Elathous bicolor (LeConte) is the only species of this genus known 

 in the larval stage. The larvae were collected from decaying wood at 

 Baldwin Hill, Douglas County, Kans., on January 3. One specimen 

 pupated on May 15 and the adult emerged June 4. 



This species is undoubtedly closely related to Athous and Lep- 

 turoides, from which it differs by the combined characters of a small 

 caudal notch and the outer urogomphal prongs being not longer 

 than the inner prongs. It bears resemblance to the larva of Ludius 

 resplendens (Eschscholtz), differing by having the outer urogomphal 

 prongs sharp and inclining forward, and by the impressions on the 

 abdominal mediotergites failing to reach the middorsal line. Distinc- 

 tion from Linionius larvae is obtained through the combination of 

 prominent outer urogomphal prongs and the presence of a dorsal 

 median groove on the ninth abdominal segment. 



The principal characters of the larva of E. bicolor may be sum- 

 marized as follows: Length 14 mm., not fully distended and probably 

 not mature. Dorsum yellow brown. Caudal notch small. Urogomphi 

 (ur, fig. 33, b; fig. 33, a) bifid; prongs subequal in length or outer 

 prongs slightly shorter than inner prongs; outer prong (opr) corni- 

 form, projecting dorsad with sharp tip inclined forward. Ninth 

 abdominal segment (fig. 33, b) with median dorsal groove (mg), 

 without setae on central dorsal area, with 3 well-rounded "teeth" on 

 each side of dorsum, and with distance between pleural area and 

 caudal notch about one-fifth total length of segment, exclusive of 

 urogomphi. Nasale with tridentate tip. Eyes present ; surrounded by 

 3 or 4 unpaired setae. Two prominent lateroepicranial setae on each 

 gena, the more dorsal seta paired with a very minute seta. Gula short 

 and narrow. One "sensory" appendix on second segment of antenna. 

 Mandible with well-developed retinaculum. Presternum of prothorax 

 undivided. Mesothorax and metathorax with definite impressions on 

 mediotergites and 3 or 4 spinelike setae on each episternum. Abdomi- 

 nal mediotergites with transverse branches of impressions reaching 

 about three-fourths of distance from longitudinal branches to mid- 

 dorsal suture, and bearing small to moderate-sized shallow pits, but 

 lacking transverse rugae. 



Material used in study. — Two examples were examined, one being 

 the exuvium of a reared specimen, the adult of which was identified 



