A Green shield bug (Palomena prasina) [1] in the Lilac (Syringa vulgaris). the adult animals use the shrub to locate partners, see also here.

References
1 Nederlands SoortenregisterPalomena prasina (Green shield bug)
Syringa vulgaris (Lilac)A Green shield bug (Palomena prasina) [1] in the Lilac (Syringa vulgaris). the adult animals use the shrub to locate partners, see also here.
References
1 Nederlands Soortenregister