Groundsel is thick along the side of the partially shaded ditch. The ditch is intermittently sprayed off with herbicide and fast growing annuals like groundsel and the nettle Urtica urens spring back.
(I looked at 100 plants and found no Nyctemera larvae.
I dissected open the swollen red stem in the second photo but it was empty.
Senecio vulgaris, growing as weed in vegetable garden
Weedy in cracks of old stone brye
Growing in a crack in the side of the footpath.
Senecio vulgaris; weed on footpath margin