348 
Psyche 
[Vol. 88 
Material and Methods 
At our major study sites near Ochsenfurt, Riederau (both Bavaria, 
W. -Germany) and Gravenbruch (Hessen, W. -Germany) we found 
12 staphylinid species associated with Lasius fuliginosus (Tab. 1). 
Our investigations concentrated on the genus Pella (mainly P. 
funesta, P. laticollis and P. cognata ). Since the myrmecophilous 
behavior of these species was found to be very similar we will refer 
to the individual species only where necessary. In fact, when 
observing the beetles in the field it was usually not possible to 
identify the species precisely. We made additional observations with 
Pella humeralis, which can be found with L. fuliginosus, but which 
often also occurs near the nests of Formica polyctena (Wasmann 
1920; Kolbe 1971). 
The field observations were conducted throughout the years 
1967-1969, and sporadically in 1970-1973. In an attempt to follow 
the life cycle of the beetles in the laboratory we set up a large colony 
of Lasius fuliginosus in a laboratory nest. The culture and mainte- 
nance of these ants over a longer period of time was particularly 
difficult, because L. fuliginosus constructs carton nests with the aid 
of a special symbiontic fungus ( Cladosporium myrmecophilum) . A 
detailed description of the nest building behavior of L. fuliginosus 
and of the laboratory nest is given in Maschwitz and Holldobler 
(1970). 
In order to measure quantitatively possible trophallactic feeding 
of the myrmecophiles by their host ants, tracer experiments were 
carried out using the radioisotope 32 P mixed with honey-water. The 
quantity of marked food taken up by the ants was reflected in the 
counts per minute which were determined with a standard Geiger- 
Table l 
Staphylinids found near one nest of Lasius fuliginosus. 
Pella laticollis 
Pella lugens 
Pella cognata 
Pella funesta 
Pella humeralis 
Oxypoda vittata 
Rugilus rufipes 
Thiasophila inquilina 
Homoeusa acuminata 
Sipalia circellaris 
A theta fungi 
A theta sodalis 
