1982] 
Buschinger — Leptothorax faberi 
207 
the contrary, seems to make a mating flight. As with European L. 
acervorum, I could never induce mating in any kind of flight cage in 
the laboratory. 
4 Discussion 
The biology of Leptothorax faberi deserves to be discussed with 
respect to several features. 
First of all, I am fairly convinced that this species represents an 
obligatorily parasitic ant. It seems unreasonable to assume that the 
one queen originally found should have run into the “muscorum” 
nest by chance during collecting, that it would have been accepted 
there, and that it could reproduce within the foreign nest. The very 
low number of only two workers produced in two colonies is 
another datum in favor of the opinion that L. faberi is a parasitic 
ant. 
Finally, the presence of a postpetiolar ventral spine also supports 
this hypothesis, since most parasitic species among the Feptothora- 
cini have it. 
The production of host species sexuals within the parasitized col- 
ony even in its third laboratory brood period indicates that a host 
species queen must have been present. This was not checked by 
dissection, but several dealate host species females were living in the 
nest when it was collected. Thus, L. faberi seems to live as an inqui- 
line ant alongside the fertile host colony queen(s), as do Dorono- 
myrmex pads, Leptothorax goesswaldi, L. kutteri, and others. 
Inquilines, however, are usually workerless. In Doronomyrmex 
pads and Leptothorax kutteri, the worker caste is completely lack- 
ing in the vast majority of all the colonies we ever collected or kept 
in the laboratory, this being several dozen of D. pads and about 100 
of L. kutteri. However, a total of 2 or 3 workers of both species have 
been produced in laboratory culture, and one L. kutteri worker was 
found in a field colony (Bruckner, in litt.). At present, it is impossi- 
ble to decide whether the two L. faberi workers represent such rare 
exceptions, or whether the species usually will produce some more 
workers. 
I also doubt that the exceptionally high ratio of males/ females in 
the offspring of L. faberi represents the natural condition. Addi- 
tional material must be collected in the field to clarify these 
problems. 
