NO. II LARVAE OF THE ELATERID BEETLES GLEN 175 



area approximating one-sixth of total length of segment, exclusive 

 of urogomphi. Frontoclypeal area bluntly rounded posteriorly. With- 

 out setae ventrally on basal segment of labial palpus. Third segment 

 of antenna as long as second segment. With 3 or 4 spinelike setae 

 on each episternum of mesothorax and metathorax. Abdominal 

 mediotergites with impressions extending to the middorsal suture 

 on second to eighth segments, inclusive, and with 5 to 7 prominent 

 setae in posterior transverse row, none definitely paired. 



Material used in study. — Four larvae were examined, one from 

 Dyrehaven, Denmark, and three from Lossnig (near Leipzig), Ger- 

 many. The German specimens were labeled "reared," but adults and 

 larval exuviae of reared specimens were not available to the writer. 

 (Canadian national, U. S. National Museum, and van Emden collec- 

 tions.) 



THE ATHOUS CUCULLATUS GROUP 

 Figures 12, a; 35 



KEY TO SPECIES 



1. Ninth abdominal segment (fig. 35, c) with large deep pits on dorsum; 



larva usually dark brown; urogomphi with outer prongs slightly 

 shorter than inner prongs (fig. 35, c, d) ; Manitoba and Minnesota 



to Atlantic coast cucullatus (Say) 



Ninth abdominal segment (fig. 35, /) with small, sparse punctures on 

 dorsum; larva yellowish brown; urogomphi with prongs subequal 

 in length 2 



2. Abdominal mediotergites with the 2 most medial setae occurring close 



together in a definite "paired" arrangement (fig. 35, e) ; known from 



Illinois and Tennessee to Atlantic coast scapularis (Say) 



Abdominal mediotergites with the 2 most medial setae well separated, 

 not more than "semipaired" ; British Columbia and Alberta to Cali- 

 fornia and Arizona nigropilis Motschulsky 



On the basis of larval characters, the three North American spe- 

 cies listed above have been placed in the same group, but scapularis 

 and nigropilis are most closely allied. The larvae of all species have 

 been identified through rearing. 



These are all forest forms, the larvae occurring chiefly in decaying 

 wood. Rearing records and adult captures indicate that pupation 

 normally occurs in early summer, the adults being most numerous in 

 July. 



Larvae of the cucidlatus group differ from all other known elaterid 

 larvae in the mandible (fig. 35, a), which bears a prominent medial 

 expansion in the region of the penicillus. However, the larvae may 

 be more easily recognized by the following combination of characters : 

 Caudal notch large {en, fig. 35, c, f), only slightly narrowed pos- 



