The invention relates to novel substituted 1H-pyrrole-2,5-diones of the formula (IA)
in which A′, Ar′ and R′ are as defined in the description, to novel compositions for controlling animal pests based on substituted 1H-pyrrole-2,5-diones of the formulae (I) and (IA)
in which A, A′, Ar, Ar′, R and R′ are as defined in the description, and to processes for their preparation.