Please remember the birds. Asters, tall sedums and other summer plants carry plenty of seeds, which are vital for seed-eating birds such as goldfinches and sparrows. Dying vegetation also harbours insects and spiders food for wrens, titmice, robins, 写真, and other insect-eating birds. So if you leave those untouched for now, the birds will flourish.
You’ve discovered the Cabbage Moth, Mamestra brassicae. The caterpillars grow about 50mm long before pupating: they’re common greenhouse pests, feeding voraciously at night, so visit your greenhouse after dark with a torch. The larvae will then be easy to remove and destroy. ある意味で, it’s a shame because they’re handsome insects.