220 
Psyche 
[December 
Batrisodes are probably ecologically equivalent. Such 
identity and parallelism when investigated more fully 
should further our imperfect understanding of host-guest 
interrelations within the nest biocoenose. 
In such a populous community as a F. ulkei nest it is 
expected that many species stray into the mound, or are 
taken in by the ants. The cases of Harpalus pleuriticus, 
Amara polita and Cathartus advena may indicate such acci- 
dental circumstance, penetration for purposes of hiberna- 
tion, or passing the day within the nest in the case of a 
nocturnal form such as polita. Other species may pass a 
part of their life cycle in the mounds, either accidentally 
(Melanotus communis ), or habitually ( Microdon larvae). 
The larvae and pupae of Phyllophaga horni and other species 
not yet determined are rather abundant in the nests. Their 
presence may or may not be significant, but since many 
other scarabaeids are myrmecocolous, exclusive of the 
Cremastocheilini, (Riley, * 1882 ; Smith, 1886; Schwarz, 
1889; Wickham, 1892, 1896; Wheeler, 1908, 1926; Donis- 
thorpe, 1927) more investigation is needed in the case of 
the May-beetles. 
The presence of the chrysomelid larvae of Coscinoptera 
dominicana in the Wisconsin ulkei mounds (Riley, 1882?; 
Burrill and Smith, 1919) is interesting, and suggests fur- 
ther study since the genus in North America, and in Eng- 
land and Europe related genera, are known to be myrmeco- 
colous in the larval and pupal stages (Riley, 1882; Schwarz, 
1896; Wickham, 1898; Wheeler, 1926; Donisthorpe, 1902, 
1927). 
The single record for Clivin/a bipustulata was probably 
accidental, and the beetle was undoubtedly stimulated by 
the darkness and moisture of the nest. It is a geocole by 
habit, burrowing in moist earth and mud margins of 
streams or marshes, and has been found to be nocturnal 
(Park and Keller, 1932) . When taken, the beetle was a foot 
beneath the dome of the nest, in wet clay soil with a tem- 
perature of 16 C.° In a laboratory nest it buried during 
the day and was not found by the host ants. It was attacked 
and readily put to flight by such nest predators as Megas- 
tilicus formicarius. 
