The common ragwort (Senecio jacobaea) is yet another species from the natural world that we love to hate. Ragwort pulling is an autumn preoccupation around farms and nature reserves. It presents us with two problems. Firstly it is poisonous to cattle and horses and so there is always a risk if these animals are feeding around the plant. In reality, it seems to me, cattle eat everything around the ragwort and leave the ragwort well alone. I am pretty sure I have not seen a dead cow in a field with ragwort in it!
Secondly, it is its capacity to set seeds and spread. It is a prolific plant and in some years it can be more abundant than in others but it is always abundant! You can find it on waste ground, hedgerows, pastures, dunes, downland; just about anywhere, especially if the ground is regularly disturbed or the general vegetation is sparse.
Hated by humans it may be but it is adored by insects and is another plant worth closely watching if you like insects. It is, amongst other things, the food plant of cinnabar moth caterpillars which do an amazing job of stripping everything off of the plant rendering it pretty harmless! Perhaps we should farm and spread more cinnabar moths as a biological control for this pernitious, obnoxious and useless weed?