NORTH AMERICAN GEOTRUPINAE — HOWDEN 297 



considerably both in morphology and^habits'"from"either"the Lethrini 

 or Geotrupini. Additional information on the group may show that 

 its present grouping in the subfamily Geotrupinae is illogical, but its 

 status has not been changed at present. Certainly, a heterogeneous 

 mixture of genera are included in the tribe. Because of this, general- 

 ization on the habits of the group would be useless, for the biologies of 

 only a few species are known. 



Most of the members of the tribe are nocturnal, and moderately 

 colonial, with burrows in rather restricted habitats. With the 

 exception of several species of Bolboceras (formerly Odontaeus) and the 

 European species of Bolbelasmus, which have been found to feed on 

 certain subterranean fungi, none of the adults in this large tribe has ever 

 been noted feeding, or doing much else for that matter except burrowing. 



Fabre, who accumulated many obscure facts concerning the biology 

 of the Geotrupinae, added considerably to our knowledge in his 

 writings (1919, pp. 300-330) about Bolbolasmus (formerly Bolbolceras) 

 gallicus (Mulsant). He found that the beetles dig directly down to 

 and feed on underground trufllelike fungi, one species being Hydno- 

 cystis arenaria Tulasne. He later showed, by burying bits of fungi in 

 a flower pot, that the Bolbelasmus gallicus are able to unerringly dig 

 do^vn to the food. Fabre also mentioned that when investigating the 

 burrows, which are often found in sandy pine woods, the beetles were 

 usually discovered with a bit of fungi on which they had been feeding. 

 He did not mention finding the larva. 



The onl)^ other European genus in the tribe contains one European 

 representative and a number of North American species. The genus is 

 Bolboceras, for a number of years known as Odontaeus, the European 

 species being Bolboceras mobilicornus Fabricius {=armiger Scopoli of 

 a number of authors) . 



There are several scattered references to the one European species, 

 all using the name Bolboceras armiger. Notes on the habits of this 

 species have been published by Lebedeva (1906, p. 436), Arens (1922, 

 pp. 241-246), Bedel (1911, pp. 99-100), and MuUer (1948, pp. 4-6, 

 etc.). While the works of Arens and Muller on armiger were not 

 available to me, the work of Bedel was. In it he mentions its nocturnal 

 activity and compares its feeding habits to those of Bolbelasmus 

 gallicus. He believed that armiger fed on subterranean fungi, such as 

 some of the members of the genus Rhizopogon. He wrote nothing 

 about the larval habits. 



One very questionable observation on armiger was reported by 

 Saunders (1936, p. 178). A non entomological friend, after using worm 

 killer on his lawn, found a number of dead Bolboceras armiger beside 

 what he thought were worm holes. From this rather secondhand 

 information, Saunders concluded that they did not burrow but used 



