1935] 
Beetles Associated with Ants 
221 
Three of the small phalacrid beetle, Stilbus probatus , 4 
were taken on September 13, 1932, from one part of a deep 
ulkei gallery, and six more from another nest at a depth 
of four feet on June 2, 1934. Their presence with ulkei 
was the only datum obtained, however, the records are of 
interest. 
The small Atheta polita , belonging to a tribe of staphy- 
linids which includes many habitual myrmecocoles, is an 
all year resident of the ulkei nest. However, little is known 
concerning it. It is capable of making short evening flights, 
and in artificial nests easily evades the ants. Its food and 
ecological position within the nest society are unknown. 
Although it occurs elsewhere in some abundance, its con- 
tinual presence with ulkei can hardly be accidental. 
The exact status of another staphylinid, Gastrolobium 
bicolor , is also uncertain. It has been taken twice in the 
nests. A male and female were obtained on May 7, and a 
third beetle on August 20, 1932. These records are prob- 
ably accidental since the species is widely distributed over 
the Chicago Area, where it inhabits moist forest floors and 
stream margins beneath logs and stones. In the laboratory 
the beetles avoided the host ants, running away with up- 
lifted abdomens. On the night of May 18 one of the beetles 
attacked and dismembered and devoured three Batrisodes 
globosus. Since the latter fills a constant niche in the ulkei 
society we see the possibilities for disturbing the equilib- 
rium of the biocoenose arising from even accidental pene- 
tration by a non-myrmecocolous predator. 
The role of Leptinus testaceus 5 is poorly understood, 
chiefly due to its presence in such a variety of habitats. It 
is found within the nests of small forest mammals, bird 
nests, certain of the social wasps, bees and ants and in 
isolated log mold, not harboring mammals. Such a list 
provokes inquiry as to the natural niche of the species, 
especially in view of the probable ectoparasitism of related 
4 The first lot were collected by the writer, and the second group by 
Mr, Strohecker. Both lots were independently determined by the 
writer, and by Mr. Emil Liljeblad of the Field Museum. 
5 In 1929 the following' data were unfortunately omitted. Donis- 
thorpe (1909) records three collectings of Leptinus testaceus with 
Lasius fuliginosus but states that it is usually taken in nests of bees, 
birds, moles and small rodents. 
