On wild parsnip (Pastinaca sativa). The wild parsnip plant, a non-native species has been spreading with abandon in recent decades. It is a beautiful tall plant and is a favoured by the black swallowtail butterfly as a larval host. However, the parsnip can take over a site leaving no room for other plants to grow. In addition, if you get any of the sap on your skin and the skin is hit by the sun, nasty blistering burns can appear. It is fine to touch the plant (I do it all the time), just avoid breaking stems which releases the sap. These little moth caterpillars (there are five of them here), are working hard to consume the seeds of the plant, helping to control its spread. Most of the parsnip I saw on the walk had the distinctive web nests of the caterpillars, so they are doing their job, but we just need more of them!