268 Psyche [Voi. 93 
l \ 5 * a 
$ if. * ' < * Hitt 
Fig. 6: Karyotypes of a: Epimyrma kraussei from pop. no. 5b (Aude, S’France) 
and b: Epimyrma ravouxi from pop. no. 12a (Lago di Como, N’ltaly). 
Most striking is the fact, that our 1 1 field colonies of E. vandeli 
did not contain any E.-$$. This corresponds to the original de- 
scription of 6 colonies without 5$ (Vandel 1927). In laboratory 
culture, however, we obtained a few $$ from colonies of this 
population (see below). 
Workerlessness is also found in a certain amount of colonies in 
most populations of E. kraussei. In part, this is due to the fact the 
newly founded colonies do not yet contain £.-$$, and most of our 
collecting was done in spring during the time of colony foundation. 
Therefore, it is not surprising that the population of E.foreli is the 
only one where all colonies contained at least one E. $ : The sample 
was entirely collected in the fall. On the contrary, our material from 
the type locality of E. vandeli was collected in spring, and in 3 of the 
11 colonies the E.-Q was still engaged in throttling the Temno- 
thorax queen. A few more colonies may as well have been incipient 
ones, where the host queen had already been eliminated. Further- 
more, 3 colonies in the laboratory produced unusually high 
amounts of E.-$$, and when dissected, the queens proved to be 
poorly inseminated, having very few sperm cells in their receptacula. 
The lack of £.-$$ in our sample is thus at least in part explained by 
these facts. 
The highly variable average and median values of $ -numbers as 
well as the maximum values in other populations are also very 
remarkable. In some populations, like that of E.foreli, but also at 
