Ragwort Control

[The Woodman]

Does anyone in WABland or beyond know of or had experience of, the control of Ragwort using Cinnabar Moth larvae?

Any information gratefully received.

[Wild-Woman]

The Cinnabars Moth caterpillars, where I work, were not plentiful enough to cope with the huge amount of ragwort that grew this year, even though there were many thousands.
I think Ragwort has had a surge this year. Never seen so much.

[Littlesparrow]

From what i have seen locally the caterpillars strip the leaves off some plants but it doesn't kill the plant and some ragwort plants do not have any caterpillars on them so can still flower and seed.

[Cotham Marble]

Originally Posted by The Woodman

Does anyone in WABland or beyond know of or had experience of, the control of Ragwort using Cinnabar Moth larvae? Any information gratefully received.

Unhelpful answer - No.

Possibly slightly more helpful answer - The relationship between the cinnabar moth and ragwort seems not to be a simple animal eats plant/end of plant equation. Each ragwort plant, if left unchecked by damage will go through a biennial cycle, exhausting its rootstock in the process of flowering/seeding, however if this biennial cycle is inhibited by damage to the upper parts of the plant, the basal rossette and rootstock fall back to the first year setting of building the rootstock as the energy source flowering in the subsequent year (or years if the damage cycle is repeated !). From the moth's persepective it means that if it's timing is right it can effectively ensure a perpetual supply of its food plant merely by eating the plant.

For what it's worth my observation is that there were very few cinnabar moths on the wing this year and very few larvae active, meaning that many ragwort plants have flowered and have/are setting seed. It will be interesting to see what effect this has, my guess is that ragwort will be less obvious next year, but will flower in abundance the year after.

CM

[Dorts]

I have a lot of Ragwort here on the farm, which I have just about finished pulling; but have not seen a single Cinnabar Moth larvae. Could certainly do with a few, but as has been said, which is also my experience, they seem to thrive on the plants while not killing them. Ragwort is a tough-old species.
Dorts.

[Wild-Woman]

I hope the mods don't mind me adding this link from Buglife but there's so much information about ragwort here, it would be impossible for me to remember it and write it 'in my own words'.
Buglife | Ragwort | Ragwort Fact File

[The Woodman]

W-W, Littlesparrow, CM and Dorts

Thank you all for commenting, some very interesting info and links indeed.

I agree with your reasoning, CM, from my own limited field observations. Like Dorts observation, the population of Cinnabar in this area appear to be low this year and since my recent interest in this matter, I have not seen a single larva.

The BugLife link was extremely interesting. Some good stuff in there. W-W, I see no harm in promoting or direction to a link - I do it regularly - as you say it prevents repetition etc.

The flea beetle looks more promising as a method of suppression. It's fascinating - the more you look, the more answers there are!

Thanks to all.

[The Woodman]

Have come across this company

Ragwort-UK Ltd.

[JennyS]

Just a couple of gentle reminders ......

Ragwort is only a danger when included in hay or silage - grazing animals leave it well alone as can be seen in fields where the surrounding vegetation has been eaten, leaving the Ragwort plants standing in proud isolation!

Its not only an important host plant for Cinnabar caterpillars, NHM 'Hosts' lists 21 species of moths in the UK alone that use Ragwort.

Its a vital nectar source for many moths and other insect species ...

[The Woodman]

JennyS, good valid points about ragwort and its benefits to invertebrates.

I was tasked by a client who manages the county's road transport infrastructure to investigate bio-control. I have presented a report following research into the subject and on balance, I think it's fair to say that in this case a "do nothing option" is worthy of consideration.

Since starting this thread, I have looked at hundreds of ragwort plants and not seen a Cinnabar larva! I posted the link for others' interest, the discovery of the company has quelled my thoughts about turning my greenhouse into a larvae production research unit!