Corylobium avellanae apterae are usually yellowish-green but in one form the aphid is mottled with red. For additional information see ‘Further info’ link below.

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Woodland and other areas where Hazel is present. It mainly feeds on the fast-growing shoots and only rarely on the leaves.

When Hazel is in leaf.

Corylobium avellanae does not host alternate but spends its entire life cycle on Hazel (Corylus avellana). Sexual forms occur in autumn and overwintering eggs are laid on Hazel. 

True status in Britain is difficult to determine due to lack of records.

Rarely recorded in Leicestershire and Rutland.

https://influentialpoints.com/Gallery/Corylobium_avellanae_Large_hazel_aphid.htm