NO. II LARVAE OF THE ELATERID BEETLES GLEN l6l 



LIMONIUS PECTORALIS LeConte 

 Figure 31, a, e, g 



This northern species is known from Alaska and from coast to 

 coast in Canada. Larvae have been reared from Cleeves, Saskatche- 

 wan. 



This species is of considerable economic importance in the park- 

 lands of northern Saskatchewan and the Peace River Block of Alberta 

 and British Columbia. As reported by King (1928, p. 704), pccto- 

 ralis appears to be definitely associated with deep, rich, loam soils, and 

 somewhat low-lying situations, and under native conditions prefers 

 the grassy margins of snowberry (Symphoricarpos) thickets. 



After a lengthy period of drought larvae were found on June 30 

 as deep as 19 inches in an old bromegrass field. However, it would 

 appear that pupation occurs much nearer the soil surface, since over- 

 wintering adults have been taken at depths between 2 and 4 inches. 

 Rearing records indicate that pupation occurs in late summer or early 

 autumn, but the exact time is not known. 



The larva of pectoralis differs from other known elaterids in having 

 2 prominent conical protuberances on the dorsum of the ninth abdomi- 

 nal segment {pro, fig. 31, c, g). The nasale (fig. 31, a) is also char- 

 acteristic, the median denticle being smaller than the lateral denticles. 



The largest larvae examined measured 14 mm. Outer prongs of 

 urogomphi {opr, fig. 31, e, g) are reduced to mere, pointed tubercles. 

 Ninth abdominal segment without a mediodorsal sulcus, without 

 "teeth" (rarely i or 2 minute swellings) on lateral aspects of dorsum, 

 and distance between caudal notch and pleural area approximates one- 

 eighth to one-sixth length of segment, exclusive of urogomphi. 

 Frontoclypeal area truncate posteriorly. Eyes absent. Two unpaired 

 lateroepicranial setae on each gena. Mandible of common lepturoidine 

 type, with well-developed retinaculum. One small seta on ventral sur- 

 face of basal segment of labial palpus. Mesothorax and metathorax 

 with impressions indistinct on mediotergites, and with 4 to 6 spinelike 

 setae on each episternum. Abdominal mediotergites with impressions 

 reaching the middorsal suture on second to eighth segments, with fine, 

 scattered punctures, and with 3 pairs of setae in posterior trans- 

 verse row. 



Material used in study. — Fifteen examples were examined, includ- 

 ing the larval exuviae of two reared specimens. All the material was 

 from the parklands of Saskatchewan except 7 larvae from Fair- 

 banks, Alaska. The following notes pertain to the reared material : 



2; Cleeves, Saskatchewan; (no date) ; both reared to adults by Nov. 15, 1926; 

 K. M. King. (C. N. C) 



