The present invention relates to N-acrylimino compound of formula (I): wherein X is O or S, in particular O; Het is a 5-or 6-membered carbon-bound or nitrogen-bound heterocyclic ring, W1-W2-W3-W4 represents a carbon chain group connected to N and C=N, and thus forming a saturated, unsaturated, or partially unsaturated 5 or 6 membered nitrogen containing heterocycle, wherein W1, W2, W3 and W4 each individually represent CRvRw, R1, R 2 may be hydrogen, halogen, etc. R3 is selected from the group consisting of hydrogen, halogen, CN, C1-C6-alkyl, etc. R4 is selected from the group consisting of hydrogen, halogen, CN, C1-C10-alkyl, etc. R5 is selected from the group consisting of hydrogen CN, C1-C10-alkyl, C2-C10-alkenyl C3-C8-cycloalkyl, S(O)nNR9aR9b, O-NR9aR9b, NR9aR9b, NR9a NR9aR9b, NR9aC(=O)R7a, NR9aC(=S)R7a, NR9aC(=O)NR9aR9b, NR9aC(=S)NR9aR9b, C(=O)OR8, C(=O)NR9aR9b, C(=S)NR9aR9b, C(=O)R7a, C(=S)R7a, a moitey Q-phenyl, where the phenyl ring is optionally substituted with 1, 2, 3, 4 or 5 identical or different substituents R10, and a moiety Q-HetNo. where HetNo. represents a 3- to 10- membered saturated, partly saturated or unsaturated aromatic heterocyclic ring. The invention also relates to the use of the N-acrylimino heterocyclic compounds, their stereoisomers, their tautomers and their salts,for combating invertebrate pests. Furthermore the invention relates also to methods of combating invertebrate pests, which comprises applying such compounds.