LARVAL TAXONOMY OF THE TROGINAE IN NORTH AMERICA 19 



The above life history data are similar to those of Leefmans (1932). 

 According to his data, eggs of T. costatus Wied. required about 8 

 days before hatching occurred. The larvae pupated about 31 to 42 

 days later. The pupal stage had a duration of about 11 to 12 days, 

 and the adult quiescent period varied from 10 to 13 days. 



Keys to the Known Third (Final) Stage Larvae 



The keys presented below separate the final or third stage lar\'ae of 

 14 species and four groups of two and three species each. The four 

 species groups have the following compositions: scaber and fascifer; 

 spinulosus dentibius and foveicollis; plicatus, robinsoni, and tuber culatus; asper, 

 punctatus, and carinatus. The known ranges of certain of the species in 

 the above groups are mutually exclusive, at least in part. The larvae 

 could be tentatively identified, therefore, on this basis. See Vaurie 

 (1955), Howden and Vaurie (1957) and Vaurie (1958) for the known 

 ranges of the species of Trox and Omorgus in North America. 



KEY TO THE GENERA 



Spiracles biforous (fig. 56). Antenna with distal sensory cone on 

 segment 2 (fig. 20). Maxillar/ stridulatory area with curved 

 double row or patch of stridulatory teeth (figs. 41 and 42). Trox 



Spiracles cribriform (fig. 59). Antenna without sensory cone, with 

 slightly concave distal sensory area on segment 2 (fig. 21). 

 Maxillary stridulatory area with single straight row of stridu- 

 latory teeth (fig. 49) Omorgus 



KEY TO THE KNOWN THIRD STAGE LARVAE OF TROX 



1 . Epipharynx with 4 smaller sensory spots distad of 2 larger, setiferous 



sensory spots on haptomicrum (figs. 3, 6, and 8). \Vith only 2 

 sensory spots on pedium distad of slightly arching, transverse row 



of sensory spots (figs. 3, 6, and 8) 2 



Epipharynx with 2 smaller sensory spots distad of 2 larger, setiferous 

 sensory spots on haptomerum (figs. 2, 4, 5, and 7). With 4 sensory 

 spots on pedium distad of slightly arching, transverse row of 

 sensory spots (figs. 2, 4, 5, and 7) 4 



2. Dorsal lobe 1 (DLl) of abdominal segments 1 to 4 with transverse, 



irregular double row of about 25 to 40 spinules (fig. 37). With 

 prominent median epicranial setae (fig. 1) atrox 



