Stripey Caterpillars on Yellow Flowers

These past few weeks you might have seen some tall-ish green plants with bright yellow flowers at the top. They grow in fields and rough ground all through the summer and one place you can find them a lot is by the sides of roads. This plant is called ragwort. Sometimes ragwort has stripey yellow caterpillars on it. This summer I have noticed lots of ragwort and lots of caterpillars. Maybe like you, I had no idea what these were called. It turns out they are called Cinnabar Moth Caterpillars and they are rather special.

Normally small animals want to be colours that help them hide in the places that they live. Yellow and black is a funny colour if you want to hide on green plant stems and leaves; its a very loud colour mix that can be seen easily! Do you know of other animals that are yellow and black striped? Bees and wasps are too and, as every small boy and girl knows, these insects are dangerous and have nasty stings. They don’t need to hide - their stripes are a warning to other animals. The stripey caterpillar is saying the same thing to other creatures, particularly to small birds who might want to eat it as a tasty snack. It is saying “Watch out, you might not like the taste of me!” and they are right - because the caterpillars don’t taste nice and are poisonous to things who eat them.

Here is the really clever bit; how do these little caterpillars become poisonous? They are not born that way. They eat the leaves of a poisonous plant and become poisonous themselves. Which plant? Ragwort! Ragwort tastes bad and is poisonous to animals who try to eat it, even big animals like horses, so obviously don’t try that yourself, but it is not poisonous to Cinnabar Moth caterpillars and I suppose that they must like the taste of it because they eat a lot of it - many ragwort plants I have seen these past few days have had all the leaves chomped off!

Just as in the story everybody knows, The Very Hungry Caterpillar, eventually these stripey caterpillars make a cocoon for themselves and then turn into a beautiful butterfly. Well not a butterfly actually in this case but a moth. A Cinnabar Moth is a moth that flies in the daytime, unlike most moths who fly at night time, and it also looks a lot more pretty than most moths do. It is poisonous too, which is why it is not worried about having a beautiful bright red colour on it. Here is a picture of what one looks like, but I didn’t take it:

Image courtesy of Wikimedia Commons | Taken by Svdmolen

In the next few weeks there should be a lot less caterpillars and a lot more moths so maybe I will find some and take a photo of one myself to show you. In the meantime have a look and see if you can find any ragwort, caterpillars or moths like these where you live.

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