Crazy Coloured Caterpillars

Cinnabar Moth Caterpillers on Ragwort
Cinnabar Moth Caterpillers on Ragwort

Found a few of these little beauties devouring the Ragwort near the car park during lunchtime. They’re caterpillars of the Cinnabar Moth (Tyria jacobaeae) and even though they are bright yellow and black are surprising hard to spot while the wind is blowing the vegetation all over the place.

The moth itself is a beautiful deep green / black and ‘cinnabar’ red and lays about 30-60 eggs on the underside of the Ragwort leaves. These then hatch all at once and the caterpillars are so voracious that it’s not unusual for them to either die due to lack of food (they eat so much of it) or turn cannibalistic. I’d not heard of caterpillers eating their egg mates but I suppose in a strange way it ensures the survival of the species.

The yellow and black colouring is, as normal, a warning that they are toxic and “do not eat me” which they gain from the Ragworth leaves.


  1. katy sweeney said:

    i have recently found at least three hundred of theese cattiplilars in my garden i have noticed the moths too but they have seemed to have gone now. is there any tips or help you can give me to keep them safe i have a butterfly house that i have ordered and soon will be ariving is it ok to put them in there or best to leave them were they are as they are basically covering my lawn . also i dont have well at leadt i dont think i have got any of that plant that they seem to like
    thank you look foward to hearing from you katy

    July 7, 2010
  2. Stu said:

    Hi Katy

    The chances are they’re on the move to find some more food, ragwort. Don’t worry about there being lots of them as it’s very rare for them all to pupate as they usually eat the food before most of them get that far and then they’ll either move to find more or (and this is the grim bit) start to eat each other.

    When I was a kid, many many year ago, we managed to keep a few to pupae stage by supplying them with ragwort for them to eat – if there’s food – they’ll stay. A butterfly house is a great idea though but with 300 you’re going to have to find a LOT of food 🙂

    Thanks for popping by,


    July 7, 2010
  3. siona said:

    i have a black and yellow caterpiller in my house becouse my brother found them in the garden and he is wondering does it bite or does it suck blood he is dum tho so dunno wa he is on about so can you reply jst to keep him happy thank you for reading

    July 19, 2010
  4. Stu said:

    Hehe – nope – they’re completely harmless – unless you eat them 🙂

    July 24, 2010
  5. jessica said:

    Hi we have lots of the caterpillars in my garden the same as the picture we are not sure what they are as we have only just started find out about things in the garden can you help thanks jessica

    July 26, 2010
  6. Stu said:

    Hi Jessica

    They’re either going to be Cinnabar Moth or Burnett Moth caterpillars.

    Thanks for visiting.


    July 26, 2010

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