Ragwort is a common plant which grows in many environments especially on wasteland and fields that are under grazed.  It is very toxic especially to livestock like horses and the seeds can easily blow onto their fields and can remain dormant for over 15 years, so it needs careful management.  However it is a very important source of nectar and pollen for many species including 30 which are entirely reliant on ragwort.  Cinnabar caterpillars can denude a plant very quickly and usually by July there are many large caterpillars but these are the first I have seen. There were also several flies and soldier beetles on the flowers in the extra.