Nitro-substituted heterocyclic compounds of the formula (I) ##STR1## wherein R is hydrogen or alkyl, Z is an optionally substituted aryl or optionally substituted heterocyclic group containing at least one atom selected from N, O and S,A is optionally substituted ethylene or optionally substituted trimethylene, andB stands for 2 or 3 members of a heterocyclic ring which is formed, together with the adjacent C-atom and N-atom and at least one of said members may represent a hetero atom and may be optionally substituted, provided that when B stands for 3 members, two of which are carbon atoms and the other one is a nitrogen atom which is located in the middle of the three members, then at least one of said two carbon atoms must be substituted by a keto group. Such compounds being useful as insecticides.