Very large scale insects on Lime tree

Very large scale insects on Lime tree

Observation - Very large scale insects on Lime tree - UK and Ireland. Description: Noticed many of these rather scary sized insects on lime, Tilia × europaea trees in a London park. I neglected to include something for scale (boom boom!) but they were about 15mm across.

Noticed many of these rather scary sized insects on lime, Tilia × europaea trees in a London park. I neglected to include something for scale (boom boom!) but they were about 15mm across.