Carboxylic acid derivatives of the general formula I ##STR1## where R.sup.1 and R.sup.2 are each C.sub.1 -C.sub.4 -alkyl, C.sub.1 -C.sub.4 -haloalkyl, C.sub.1 -C.sub.4 -alkoxy, C.sub.1 -C.sub.4 -haloalkoxy and/or C.sub.1 -C.sub.4 -alkylthio;R.sup.3 is hydrogen, hydroxyl, cyano, nitro, formyl, halogen, unsubstituted or substituted amino, C.sub.1 -C.sub.4 -alkyl, C.sub.1 -C.sub.4 -alkoxy, C.sub.3 -C.sub.6 -alkenyl, C.sub.3 -C.sub.6 -alkenyloxy, C.sub.3 -C.sub.6 -alkynyl or C.sub.3 -C.sub.6 -alkynyloxy;R.sup.4 is hydrogen or C.sub.1 -C.sub.4 -alkyl;R.sup.5 is unsubstituted or substituted five-membered hetaryl or isoxazolinyl or --CR.sup.6 .dbd.NOR.sup.7 ;R.sup.6 is hydrogen or unsubstituted or substituted C.sub.1 -C.sub.4 -alkyl, C.sub.3 -C.sub.8 -cycloalkyl or phenyl;R.sup.7 is unsubstituted or substituted C.sub.1 -C.sub.4 -alkyl, C.sub.3 -C.sub.6 -alkenyl, C.sub.3 -C.sub.8 -cycloalkyl or phenyl;A is oxygen or sulfur;X is nitrogen or methine .dbd.CR.sup.8 --;R.sup.8 is one of the radicals R.sup.3, or R.sup.8 and R.sup.3 together form unsubstituted or substituted 1,3-butadiene-1,4-yl or aza-1,3-butadiene-1,4-yl, andY and Z are each nitrogen or methine .dbd.CH--, their preparation and agents containing them.