Friday, 2 July 2010

Cinnabar moths and caterpillars

ResearchBlogging.orgDuring a walk in my local wildlife garden we noticed the first Cinnabar Moth (Tyria jacobaeae) caterpillars of the year, and an adult also flew by. The caterpillars clustered at the flower heads of Ragwort (Senecio jacobaea), which they prefer as food, and had defoliated the plants quite a bit. Many had already left in search for greener pastures and were around the ground or wandering over other plants. Cinnabar Moth caterpillars have a strong tendency to cluster together, an antipredator behaviour.
This behaviour , however, gradually dissapears as the larvae grow so that fully grown fifth instar larvae are actually agressive to each other and tend to be found spaced out in the plants.
Adults emerge in late spring from overwintering pupae and after mating, female lay eggs in the basal leaves of ragworts. Larvae hatch in about two weeks and their development takes about one month, after this, they pupate on the ground and remain in diapause until the following spring.
This moth is often active by day and therefore easy to spot due to its contrasting coloration, but they are most active at dawn and dusk. When they fly, their pink hindwings are quite apparent and they can be taken for some exotic bright pink butterfly. The bright colours of the moth and particularly, the striking yellow and black stripy pattern of the larvae are a warning sign of their distastefulness to vertebrate predators, a phenomenon called aposematism. The larvae ingests and stores in its tissues toxic alkaloids from the foodplant and the adult also synthesizes additional toxins itself. Surprisingly, many invertebrate predators feed on eggs and caterpillars of this moth.
Given that Ragwort is a toxic plant for horses and has been introduced in several countries where it has become an invasive weed, a lot of effort has been directed to study the ecology of the Cinnabar Moth as a way of controlling Ragwort.

More information
J.P. Dempster (1982). The Ecology of the Cinnabar Moth, Tyria jacobaeae L. (Lepidoptera: Arctiidae) Advances in Ecological Research, 12, 1-36 DOI: 10.1016/S0065-2504(08)60076-8


JayLeigh said...

This is a great blog entry! I think cinnabar caterpillars and moths are such interesting little creatures. I found your blog on Google when searching for information about cinnabar caterpillars for my blog entry about them. I added a link to your blog at the end of it. (Here it is in case you want to take a peek: )

Blackbird said...

Thank you Jay! I am glad it was informative. I have never tried to keep them, but I think after reading your post you guys probably got a large caterpillar ready to pupate. I would try and find small ones next year to show the kids how much they eat and how fast they grow.

Anonymous said...

I've found some caterpillars from ragwort that has been pulled and is ready for burning. Now how do I help them survive so they can eat more ragwort - a breeeding program would be good.

We're overrun with ragwort now, and there are very few caterpillars. I remember there being loads of caterpillars and them stripping whole plants of ragwort.

Anonymous said...

i found some of these caterpillars on some ragwort by the beach, i took them home and i am now waiting for them to pupae. they also eat common groundsel but they prefer ragwort. its a shame they take a year to evolve but its worth it when youve got a ragwort infestation!

Steph said...

We have found some of these caterpillars and I'm wanting to keep them to show my children see how they change. We found 3, and I would like to know some more info on how I can help them grow n keep them. Please can you help as it would be lovely for the kids see them grow n change
Cheers, steph

Anonymous said...

I'm infested all year every year in my garden. Anybody who wants them come take them gladly :P x