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day 1 - 31 July
Poppy and Tilda brought 14 caterpillars in from the front garden in a little bowl, and wanted to keep them. They are about 1-1.5 cm long, black & gold striped, with black faces.

To start with, I put them in a tub, with cling film with holes in over the top, and 4 leaves from the plant they had been on. Then headed for the computer to find out a bit about them. It turns out that caterpillars can generally only eat from that plant - I'd never realised they were so choosy.

Jos, Lyn, and Janet from the UK-HOME-ED list pointed me in the right directions (thank you!) and so I learnt some about how to care for them (follow the link, click on Bug Pets, then find caterpillars), and about how to be more careful when handling them. I also found out more about Cinnabar moths and their caterpillars.
 

day 2 - 1 August
This morning they had eaten the 4 ragwort leaves they had had, and I realised they would need a fair amount of stuff in their home if I wasn't to be restocking it with leaves all the time. So I reluctantly emptied out the large Quality Street jar in which I'd been collecting all our change, and it has now become a caterpillar habitat.
 

The ragwort stems go into a little pot of water, which has cotton wool in the top to stop the caterpillars drowning, and there are pebbles on that to make it nicer for them.  There are larger pebbles around the pot, to secure it, and also because apparently these caterpillars like to pupate in the debris at the bottom of the plants - crevices in stones, and suchlike places. There are some dry twigs to make it easier for the caterpillars to climb back up onto the plants.

day 3 - 2 August
Didn't have to do much today, because there was still plenty of ragwort in the jar. Spent a lot of time just watching them - I'm fascinated. (The girls aren't quite so fascinated!) They have grown considerably since 2 days ago, and the biggest are now about 2 cm long when stretched out. There is one little runt of a caterpillar which is not growing like the others, and is often down at the bottom of the jar on the stones.

The caterpillars definitely prefer to eat the flowers rather than the leaves - most of them are up at the flowers, munching away. They will eat the entire flower, so it will not produce seeds, which is why they are used to help control ragwort.
 

day 4 - 3 August
Changed their food again today. There aren't so many flowers on these stalks, so I hope they still eat plenty. I thought Runty might have died, but I counted 14 again as I put the new plants in.

The caterpillars grow by moulting - they shed their old skin, having grown a wrinkled new skin underneath, and then puff themselves up to fill out the new skin. I have seen a couple leaving their shrivelled old skins behind.
 

day 5 - 4 August
Most of the flowers have been eaten, but there are still plenty of leaves left, and the caterpillars are moving downwards to eat them.

Caterpillars poo a LOT! There are loads of little (1-2 mm) balls over the plants, and down in the base of the jar. The balls are getting bigger as the caterpillars get bigger. Also, the colour varies - when they are eating the yellow flowers, their poos are brown, but when they eat the leaves, the poos are black.
 

day 6 - 5 August
They need more food, as they have nearly finished off the leaves that are there. I haven't done it yet.

OK, I've done it now. Nearly lost one! As I was changing the plants over, some caterpillars were still in the jar, and some were on the table. One made a break for freedom ... I looked around, but couldn't see it, and figured I'd find it when I cleared the newspaper and stuff up. Then Elijah came crawling in from the kitchen, and when I looked down at him, he was a couple of feet away from the table, and just about to pick something up to put in his mouth - yup, the wandering caterpillar! So, I still have 14, and I haven't had to worry about Elijah being poisoned :-)

As soon as the new ragwort was in the jar, they all went mad, climbing all over the place, getting very excited. The biggest ones are now up at the flowers again. Runty is at least on a leaf, but he is, as usual, the lowest.
 

day 7 - 6 August
I keep counting them today, and can't get anywhere near 14 ... This evening I'm down to about 11! There are quite a lot of leaves in there, so it's tricky to see them. Also, a couple of the flowers touch the netting over the top, and they keep climbing up to there, and then falling off, so there are probably one or two scurrying around on the stones. Or maybe they have just vaporised. (I think I'd notice spontaneous caterpillar combustion.) Roll call tomorrow ...
 

day 8 - 7 August
Well, this is getting exciting! There are now only 9 caterpillars on the plant (it's thinned down a lot today, so I'm pretty sure). I think the others must be getting ready to pupate. I can see 2 right at the bottom of the jar, when I lift it up and look through the base. One is in a gap between two pebbles, and one has got itself buried in the earth (and caterpillar poo) that is down there. I'll try and take a photo tomorrow. I thought earlier that I could see another one or two down amongst the debris, but they're not visible now - they might have got themselves tucked away more.

I haven't changed the ragwort today - there's still enough there to keep them going till tomorrow - because I'm a bit worried about disturbing them when they want to pupate; I don't want to scare them or make them feel it's not safe. I'll see how it goes in the morning.
 

day 9 - 8 August
Gave them new ragwort this morning, and there were definitely 9 on the plant. The two visible ones down at the base of the jar are still there, looking ever cosier, and I'm assuming the last 3 are hidden away somewhere down there too. They're always pretty frisky when I put new food in, but by midafternoon today there were still 2 or 3 running around madly. Maybe looking for a good place to overwinter?

11pm - Only 6 left on the plant! Including Runty, who seems to have a deformed head, and I'm not holding out an awful lot of hope for him. So that's 3 more gone off to pupate (I hope). One of the three has snuggled half of his body up against the side, so it should be easy to see what is going on there.
Here it is: 
 

day 10 - 9 August
Unfortunately, the helpful caterpillar pictured above has moved - presumably to a more private spot. :-P
Had a quick look this morning, and we seem to be down to 5.
 

day 14 - 13 August
Oooh - been a bit lazy these last few days - enjoying the weekend!

Over the weekend, the remaining caterpillars - except Runty, who has sadly died as expected - have disappeared from the ragwort, and are hopefully now settled down for some serious pupating.

The soil, caterpillar poo, and general debris that is in the base of the jar is starting to get rather mouldy. I don't know if this will bother the caterpillars which are trying to pupate. Also, I don't know whether to leave the cocoons (once they are formed) in the jar - with the mould, etc - or to take them out and keep them somewhere clean and dry, but presumably not too warm, till spring.

I've looked at books in the bookshop, and in the library, but haven't found anything useful about rearing caterpillars. Neither have I yet found any really relevant websites. Last night I subscribed to a couple of Yahoogroups (caterpillar and uk-leps), so I will ask for advice there.