EN
The paper presents four cases of territorial ant colonies interfering in the course of Formica sanguinea Latr. raids against slave species which nest next to or in their territories. In three cases, Formica rufa L., when protecting its own territory, forced out (one case) or held (two cases) a raiding column of F. sanguinea, thus “saving” local Formica fusca L. nests from danger. In one case, Lasius fuliginosus (Latr.) did not let a F. sanguinea column pass its territory; to reach its target (a colony of Formica cinerea Mayr), the column had to by-pass the foreign territory.