The invention relates to a method of controlling insects in which compounds of the formula ##STR1## in free form or in agrochemically acceptable salt form, are used, wherein specific insects of the order Homoptera are controlled, to the corresponding use of those compounds, to corresponding insecticidal compositions, the active ingredient of which is selected from those compounds, and to a process for the preparation of and to the use of those compositions. The invention relates also to a method of protecting plant propagation material against attack by pests, wherein compounds of formula I, in free form or in agrochemically acceptable salt form, are used, to the corresponding use of those compounds, to corresponding pesticidal compositions, the active ingredient of which is selected from those compounds, to a process for the preparation of and to the use of those compositions, and to plant propagation material correspondingly protected against attack by pests.