It was growing so well but during last weekend we noticed it seemed like it was shrinking.
As the days went by it did shrink in size and I noticed it had a little red 'pooh-like' button at the end of its body which didn't drop off. Monarch caterpillar pooh is usually quite green and is called frass, by the way.
Last night largest caterpillar was writhing on the plant and this morning it was curled up and 'kind of' still attached to the plant by an end foot.
Clearly it wasn't going to make it, so I did the kind thing and euthanised it by wrapping it in a paper towel and placing it in the freezer.
By wrapping them in a paper towel (gently but firmly) and placing it in the freezer, they can't move around and the cold sends them quickly to sleep before they freeze.
It's unfortunate to have to do it, but preferable to allowing a lovely creature to suffer.
Smallest caterpillar is a good middle-size and eating well.
Our weather has become really cold now. Where we live in New Zealand is referred to as 'the Winterless North', however today the morning temperature was 7 C (45 F), so no wonder our caterpillars are enjoying being inside our house where it's a bit warmer than that.
When the sun comes up each day, I place their plant into the sunny part of the window so they can soak up the warmth.