EN
The paper is devoted to enslavement of adult Formica cinerea cinerea Mayr workers by Formica sanguinea Latr., a phenomenon hitherto unknown under natural conditions. Suc enslavement follows periodic invasions and temporary occupation of nests of slave species by F. sanguinea. During the occupation of their nest, some F. cinerea workers join the occupants colony. The studies were made m Poland and in Finland between 1994 and 1996.