In praise of ragwort

It is that time of the year again, when irate farmers rage against neighbours who fail to control Ragwort, allowing the fruits to drift wherever the wind takes them. It is undeniably true that he plant does contain a toxin, pyrillozine, which can be fatal to cattle, but there are no reliable statistics which can be referred to. Informed opinion suggests that the number of fatalities is very small. I'm told that the taste is foul but I rely on the opinions of others for that. Certainly it appears to repel most livestock.


Certainly ragwort is much loved by entomologists and a small clump of the plant, known nowadays as Jacobaea vulgaris (previously Senecio jacobaea), was proving a magnet for insects when I visited Stefen Hill Pocket Park earlier today.


One of the most abundant was Eriothrix rufomaculata. I always find this insect on ragwort at this time of the year, but what the connection is I don't know. My photograph is poor but it does show the rust-red markings on the side of the abdomen which give the insect its specific name, for rufomaculata means, of course, red-spotted. Although in the adult stage it is a nectar feeder, the larvae are parasites of certain moths,  probably pyralids, although evidence is surprisingly limited.

Eriothrix rufomaculata, a tachinid fly very common on ragwort.

Stefen Hill Pocket Park, 29 July, 2019

I took about a dozen photographs and aborted several more at the last second. But every time I had an insect nicely lined up a butterfly would arrive and disturb my subject. How often this year have butterflies been such a problem!

A marginally better view of Eriothrix rufomaculata:

same plant, same place

The butterflies causing the trouble were, for the most part, Gatekeepers, Pyronia tithonus.

Gatekeeper butterflies are currently abundant in the pocket park.

29 July, 2019

I saw dozens of these pretty insects around; over the pocket park as a whole there must have been several hundreds.

The caterpillars of Cinnabars were present, chomping away at the leaves and stems. Its association with ragwort is reflected in its Latin name, Tyria jacobaeae. I saw none of the adults around, but the next generation appears to be secure.

Cinnabar caterpillars are toxic and thus avoided by most birds. The warning

colours say it all. Stefen Hill Pocket Park, 29 July, 2019

This moth, being day-flying and brightly coloured, is often mistaken for a butterfly. There were lots around last month on, for example,  Drayton Fields allotments, where I took this photograph. It is visiting Groundsel, Senecio vulgaris, a close relative of ragwort, no doubt about to place its eggs on the slightly succulent leaves.

I have given the impression that most of my time today was spent peering at ragwort plants. In fact I spent more time looking at leaf miners and galls in trees and shrubs - not that anything rare or exciting was found. And galls are hardly exciting features for most people unless it is something like mistletoe, technically also classed as a gall.

But who could fail to be thrilled by this example of Aceria macrochela on the leaf of a Field Maple?


Exactly!

Galls cause by the mite, Aceria macrochela. Stefen Hill Pocket Park

29 July, 2019