The present invention relates to a method for using insecticidally active bicyclic derivatives in the control of insects or representatives of the order Acarina in a plant propagation material, by applying a compound of formula Iwherein X is S, SO or SO2 R is hydrogen, halogen or C1-C4haloalkylX1 is O, S or N-R3, wherein R3 is C1-C4alkyl, C1-C4haloalkyl or C1-C6alkoxy-C1-C6alkyl, or X1 is N-(4-methoxy-benzyl) or N-(propargyl)X2 is N, CH, C-halogen, C-CN, C-O-C1-C4alkyl, N-(2-chloro-thiazol-5-ylmethyl), C-S-C1-C4alkyl, C-SO2-C1-C4alkyl, C-S-phenyl, C-SO2-phenyl or C-SO2-C1-C4halolakylR1 is C1-C4alkyl, C1-C4haloalkyl, C3-C6cycloalkyl, C3-C6halocycloalkyl, C2-C6alkenyl, C2-C6haloalkenyl or C2-C6alkynylR2 is halogen, C1-C4haloalkyl, C1-C4haloalkyl substituted by one or two hydroxy, or R2 is C1-C4haloalkylthio, C1-C4haloalkylsulfonyl, O(C1-C4haloalkyl), SF5, phenylcarbonylthio, mercapto, or C1-C4alkoxycarbonyl andR4 is hydrogen or halogenand agrochemically acceptable salts and N-oxides of those compounds.
