Compounds of the formula (I) and their stereoisomers ##STR1## wherein A, B, C' and D independently of one another denote CH or N, in which at least one of the symbols A, B, C' or D must correspond to a nitrogen atom,X denotes CH.sub.2 or oxygen,R.sup.1 denotes a radical bonded to a carbon atom from the series comprising H, trialkylsilyl, halogen, nitro, cyano, alkenyl, alkynyl, amino, cycloalkyl, phenyl, phenxy, alkoxy, alkenyloxy, alkynyloxy, hydroxycarbonyl, alkylthio, cycloalkyloxy, alkylcarbonyl, alkoxycarbonyl, alkenyloxycarbonyl, alkynyloxycarbonyl, halogenoalkyl, alkoxyalkyl, halogenoalkoxy, halogenoalkylthio, halogenoalkoxyalkyl, alkylthioalkyl, alkoxyalkoxy, halogenoalkoxyalkoxy, alkenyloxyalkoxy, halogenoalkenyloxy, alkoxyalkylthio, alkylthioalkoxy, alkylthioalkylthio, halogenoalkoxycarbonyl, halogenoalkenyloxycarbonyl or dialkylamino or two radicals R.sup.1 when they are positioned ortho to one another together denote a methylenedioxy, ethylenedioxy or alkylene radical,R.sup.2 and R.sup.3 independently of one another denote alkyl, alkenyl or phenyl, or R.sup.2 and R.sup.3 denote an alkylene chain which--together with the quaternary carbon atom-forms an unsubstituted or fluorinesubstituted ring having three to six ring members,R.sup.4 denotes --H, F, --CN, --CCl.sub.3, --C.tbd.CH, (C.sub.1 -C.sub.4)alkyl, --C--NH.sub.2, SR.sup.5 denotes pyridyl, furyl or thienyl which can all be substituted, phthalimidyl, dialkylmaleimidyl, thiophthalimidyl, dihydrophthalimidyl, tetrahydrophthalimidyl or substituted phenyl, orR.sup.4 and R.sup.5 --together with the carbon atom bridging them--denote an optionally substituted indanyl, cyclopentenoyl or cyclopentenyl radical and n denotes 0, 1 or 2, possess advantageous properties for combating pests, in particular insects and acarids. Furthermore, processes for the preparation of compounds of the formula I are described.