NORTH AMERICAN GEOTRUPINAE — ^HOWDEN 161 



a strong, light, cylindrical cage which was easily sunk to the desired 

 depth by use of a posthole digger. 



After the adult beetles had been in the cages for a month or more, 

 a portion of each cage was carefully investigated. If larvae were 

 found, they were removed along with the food material provisioned 

 by the adult and placed in 2-ounce, metal, salve boxes in which they 

 were easily observed and reared. Depth of the larval cell, instar, 

 food, and other information were recorded. Larvae were preserved 

 by placing them alive in hot water kept just under boiling, leaving 

 them there for 3 minutes, and then dropping them into vials of 70 

 percent alcohol. Various larval preservatives that contain acetic 

 acid, kerosene, and alcohol in varying proportions were not employed 

 because such preservatives caused undesirable distension of the larvae. 



Review of the subfamily Geotrupinae 



ADULT CHARACTERISTICS 



The North American representatives of the subfamily Geotrupinae 

 can be separated from other Scarabaeidae by the following charac- 

 teristics. 



Antennae 11-segmented with 3-jointed club, mandibles not hidden 

 by the clypeus, clypeus sharply delimited from the vertex, often with 

 a tubercle or horn, anterior femora with a silky spot on anterior 

 surface, pygidium largely hidden by the elytra, abdominal spiracles 

 on the membrane between sclerites, male genital armature enclosed 

 in a definite sclerotized genital capsule. 



The genus Pleocoma appears very closely related to the Geotrupinae 

 but has been omitted from the present work. 



Key to North American tribes of the subfamily Geotrupinae 



Antennal club large, about as long as the basal eight segments, rounded, convex on 

 both sides I. Bolboceratini 



Antennal club small, about half as long as the basal eight segments, elongate, not 

 convex on both sides II. Geotrupini 



I. Key to genera of North and Central American Bolboceratini 



1. Eyes entirely divided by canthus; color sometimes variegated 2 



Eyes only partially divided by canthus; color uniform brown to black . . 4 



2. Scutellum very elongate and narrow. (Central and South America). Athyreus 

 Scutellum triangular 3 



3. Color brownish orange varied with areas of black or dark brown; middle coxae 



narrowly separated by slender projection of mesosternal plate. 



Bolbocerosoma 



Color uniformly brown to black; middle coxae contiguous, not separated by 



projection of mesosternal plate Bolboceras (formerly Odontaeus) 



