Pyrazolylhetaroyl derivatives of the formula I ##STR1## where the substituents have the following meanings: L and M are hydrogen, C.sub.1 -C.sub.6 -alkyl, C.sub.2 -C.sub.6 -alkenyl, C.sub.2 -C.sub.6 -alkynyl, C.sub.1 -C.sub.4 -alkoxy, it being possible for these groups to be unsubstituted or substituted by one to five halogen atoms or C.sub.1 -C.sub.4 -alkoxy; halogen, cyano, nitro;X is oxygen or sulfur which can be substituted by one or two oxygens;n is zero, one or two; andQ, R.sup.1, R.sup.2, R.sup.3 and R.sup.4 have the meanings given in claim 1,processes for the preparation of the pyrazol-4-yl-hetaroyl derivatives, compositions comprising them, and the use of these derivatives or of the compositions comprising them for controlling weeds.