An aggregation first instar nymphs of the Green shield bug (Palomena prasina) [1] on Greater celandine (Chelidonium majus). First instars do not feed [2] and without any other information available I am not sure this is evidence of a direct plant relation.
Literature
1 Nederlands Soortenregister2 Lockwood, J. A., & Story, R. N., 1986. Adaptive functions of nymphal aggregation in the southern green stink bug, Nezara viridula (L.)(Hemiptera: Pentatomidae). Environmental Entomology, 15(3), 739-749.