NO. II LARVAE OF THE ELATERID BEETLES GLEN 89 



gomphus with i large seta ventrally, just anterad to base of inner 

 prong. 



Caudal notch (en) moderately large, U-shaped; usually not quite as 

 wide as long, slightly narrower posteriorly. 



Tenth abdominal segment (lo, fig. 20, b) with whorl of 10 fine 

 setae; usually 2 or 3 smaller setae on anterior aspect; anal aperture 

 linear and median. 



Material used in study. — Twenty-five specimens were examined. 

 These were collected from Germany (21), Finland (3), and Den- 

 mark (i). The larvae are believed to be reliably named but reared 

 adults were not available for confirmation. The material studied is 

 deposited in the Canadian national collection, the U. S. National 

 Museum, and van Emden's collection. 



LUDIUS CASTANEUS (Linnaeus) 



Figures 19, c, e; 20, c 



Elater castaneus Linnaeus, Systema naturae, ed. 10, vol. i, p. 405, 1758. 

 Ludius castaneus (Linnaeus), Eschscholtz, in Thon, Entomologisches Archiv, 



vol. 2, p. 34, 1829. 

 Corymbites castaneus (Linnaeus), Latreille, Ann. Soc. Ent. France, vol. 3, 



p. 150, 1834. 

 Corymbites (Anostirus) castaneus (Linnaeus), Schenkling, Coleopt. Cat. (ed. 



Junk), vol. 2, pt. 88, p. 364, 1927. 



The larva of this European species has been described from Den- 

 mark by Schiodte (1870, p. 521) and Henriksen (1911, pp. 265-266) 

 and referred to by BeHng (1884, p. 205). 



The larval habitat includes both soil and decaying wood. One of 

 the specimens used in the present study was taken from a stump. 

 Schiodte records the larvae as inhabiting forest meadows, and Hen- 

 riksen states (translation) : "mainly in sunny clay slopes, but also 

 found in beech stumps." The species is not referred to in the eco- 

 nomic literature. This suggests that the larvae are probably chiefly 

 predaceous, as are those of the closely related tessellatus (Linnaeus). 



In structure, the larva is very similar to that of tessellatus (Lin- 

 neaus), but may be readily distinguished by the following characters: 

 Only 2 "sensory" appendices on the second antennal segment {sap, 

 fig. ig, e) ; frons broadly rounded posteriorly; only 3 lateroepicranial 

 setae, arranged as a dorsal pair with an unpaired hair farther ventrad ; 

 gula shorter than in tessellatus; and ninth abdominal segment with a 

 deep median crease {cr, fig. 20, c) just in front of the caudal notch. 

 Henriksen (1911, p. 266) records larvae attaining a length of 21 mm., 



