Privet Hawk Larva

It frequents woodland and suburban habitats, and flies in June and July, with a single generation.
The large caterpillar is even more spectacular than the moth, being bright green with lilac and white stripes along the side, and a curved black 'horn' at the rear. It feeds on privet (Ligustrum), lilac (Syringa) and ash (Fraxinus).
Also bred by myself - at the time of writing (29th July) they are huge and just about to pupate.