LARVAL TAXONOjVIY OF THE TROGINAE IN NORTH AMERICA 15 



the induement, the adults look very much like small clods of soil or a 

 piece of the carcass or surrounding debris. The adults of some species 

 will remain motionless like this for as long as an hour; T. atrox, how- 

 ever, will move again within 2 or 3 minutes. 



The larger species, especially those of Omorgus, are usually associated 

 with carcasses, whereas the smaller species, particularly those of the 

 scaber group, are more often found in nests or burrows. Certain species 

 apparently are found only in nest and burrow habitats. Hicks (1959) 

 lists over 100 records of Trox spp. taken in bird's nests on a world- 

 wide basis. 



The carcass-feeding forms appear to prefer dried carcasses that 

 have been reduced to skin, dermal derivatives, and bone. These 

 carcasses are particularly attractive after a heavy rain. This is due 

 perhaps to the increased odor produced by the wet carcass. Heavy 

 rains also insure the presence of sufficient soil moisture for the de- 

 velopment of the larvae in the soil beneath the carcass. As many 

 as five species of Trox and Omorgus have been collected by the writer 

 beneath a single carcass. The larger species were observed feeding 

 on the hooves, skin, hair, and tendons, whereas the smaller species 

 appeared to be associated with the hair and smaller remains. 



The females of the larger species generally burrow to a greater 

 depth to lay their eggs than do females of the smaller species. A female 

 of the small T. scaber deposits her eggs at a depth of about 1.0 to 3.0 

 mm.; a female of the very large 0. texanus will burrow to a depth of 

 about 6.0 to 10.0 inches for oviposition. The eggs are usually de- 

 posited in groups of about three or four. The species laying very large 

 eggs may lay only one or two eggs at a time. The soil about the eggs 

 apparently is specially treated by the female since it evidences a 

 slightly different consistency. 



The larvae burrow vertically to the surface shortly after hatching 

 and commence to feed. The larvae are capable of rapid forward or 

 backward movement within their burrows, and when disturbed they 

 rapidly retreat to the bottoms of their burrows. The larvae pass through 

 three instars having a total duration of about 4 weeks. The active 

 third instar usually burrows slightly deeper before constructing the 

 pupal cell. Nest inhabiting species are known to construct pupal 

 "cocoons" within the walls of the nest (Robinson, in litt., cited in Vaurie, 

 1955), utilizing debris and hair to form the wall of the "cocoon." 

 Trox scaber was observed to do this in the laboratory when liberal 

 amounts of hair were intermixed in the soil of the rearing container. 



The pupal stage averages about 9 to 15 days. The callow adults 

 remain in their pupal cells for at least 2 to 3 days during which time 

 they undergo hardening and darkening processes. Some species 

 probably pass the winter or summer within the pupal cell. Others 

 evidendy emerge to feed before hibernating or aestivating. 



