Use of hydrazine derivatives of formula (I) wherein W is chlorine or trifluoromethyl; X and Y are each independently chlorine or bromine; R1 is alkyl, alkenyl, alkynyl, or cycloalkyl which may be substituted with 1 to 3 halogen atoms, or alkyl which is substituted by alkoxy; R2 and R3 are alkyl or may be taken together to form cycloalkyl which may be unsubstituted or substituted by 1 to 3 halogen atoms; R4 is hydrogen or alkyl, or the enantiomers or salts thereof, for combating non-crop pests. Use of compounds of formula (I) for the protection of non-living organic materials and for the protection of animals against non-crop pests.