BEETLE GENUS ONTHOPHAGUS — HOWDEN, CARTWRIGHT 7 



Larvae. — The pronounced hump-backed appearance is a conspic- 

 uous characteristic of the larvae of Onthophagus as in all Coprinae; 

 however, the humped back is accentuated in the larvae of Onthophagus 

 by the presence on the third abdominal segment of a dorsal conical 

 protuberance bearing numerous setae. The Iviiown larvae are all 

 very similar morphologically, the last abdominal segment exhibiting 

 some of the most useful characters for the separation of the species. 



Larval development is similar for all kno^vn species. Three instars 

 are present, each stage lasting from 8 days to 2 weeks. Development 

 from egg to teneral adult is rapid, usually taking only 5 or 6 weeks. 

 Emergence of the adults from the pupal cells may be delayed in hot 

 dry weather and during the winter. 



Construction of the brood cells is likewise rather typical. The 

 burrows, made at the edge of or under dung, are often twisted, some- 

 times branched, and vary in depth from 1 to 9 inches, depending on 

 the species. The oval brood cell, approximately^ V/o times as long as 

 w4de and filled with dung, is formed nearly horizontally at the end of 

 the burrow or branch. After the egg is fastened on end to the side of 

 a small cavity formed in the upper end of the dung, the cavity wall 

 is sealed with the same material. Tlie burrow may then be partly 

 refilled with soil and the egg and subsequent larva left without 

 further attention. 



Despite the similarity of the larvae and larval development in 

 in the various species, the study of their habits has been extremely 

 interesting because of the restricted habitat niches of a number of 

 them. A discussion of the preferred food and habitat follows the 

 description of each species. 



The species from the United States and Canada have been known 

 under many names. Various authors have used several different 

 names for the same species with resulting confusion and misidentifi.- 

 cations. Mistakes made by recognized authorities of an earlier day 

 were frequently followed by subsequent workers. We have attempted 

 to correct all such errors, added names of new species, and compiled 

 the following table in the process. 



Name used Present status 



aciculatulus Blatchley, 1928, p. 128 Valid. 



aciculatus Blatchley, 1928, p. 128 Misspelling of aciculatulus Blatchley. 



alluvius, new species Valid. 



alutaceus Blatchley, 1919, p. 31 —aciculatulus Blatchley. 



(not Wiedemann, 1823, p. 14) 



ammon Sturm, 1826, p. 177 =Copris mimitus (Drury). 



anthracinus Dejean, 1836, p. 158 Nomen nudum. 



anthracinus Harold, 1873, p. 104 =monticolus, new species and (or) al- 



(not Falderman, 1835, p. 247) luvins, new species. 



arizonensis Schaeflfer, 1909, p. 382 =hdpfneri Harold. 



arnetti, new species Valid. 



