So anyone that follows us on Twitter, or likes us on Facebook, will know that we’ve been rearing various caterpillars in the office. The WKWT office bears a passing resemblance to a 9 year old boy’s bedroom (minus all the dirty washing): we have a Natural History shelf, on which we collect interesting artefacts like broken eggs and mealworms, and we have caterpillars as pets. I told you a little about the Emperor moth caterpillars a couple of weeks ago, but now it’s the turn of the Puss Moths.
Puss Moths at first glance don’t have the most flattering name, but it actually comes from the soft, cat-like fur that they have as moth. They feed on things like poplar and willow, and just like the Emperor moths, they were incredibly greedy by the end. One in particular was about four times larger than the others. But I’m getting ahead of myself.
They start like this:
One of the best features of the Puss Moth caterpillars is their tail, which looks like two tails (see image below). When they get cross the tail whips up and little red extra tails (or extendable flagellae) pop out. If you really wind them up they can even squirt formic acid from their thorax, but that would have just been mean.
So, back to them growing up. They then turn green:
… and bigger:
I love this photo. You can see just how incredibly they eat – in perfect neat vertical rows moving along the leaf. It’s stunning to watch; it takes about 30 seconds to eat half the leaf, all the time using that mechanically ordered style. No wonder he was so huge.
And now we reach the really amazing bit. When the caterpillars are almost ready to pupate, they get really restless. In the wild they’ll wander for ages, which is why you’ll often find large caterpillars on footpaths and the like, as we did the other day. Ours just did a few laps of the pot they were living in, and then they started to turn purple:
You can see where the caterpillar’s changing colour particularly well by his head and his tail – the flecks of purple in the green. This is how we knew that this one was about to spin his cocoon. And just by my hand you can see what happens next – the caterpillar chews into the bark to create a little hole, and then spins a silk cocoon, which darkens and hardens as it dries to not only be the exact colour of the bark but also incredibly strong. The perfect camouflaged fortress. This one started to do it the very same afternoon:
That’s the very beginning of the spinning. I then went out to a meeting, and I kid you not, by the time a came back that purple caterpillar looked like this:
Isn’t that incredible?! I’m not sure I’ve ever felt so unproductive – I felt like I’d had a very successful meeting until I came back to find that a small invertebrate had built a home while I was gone!
So that’s the last you’re going to hear of our caterpillars for a little while I’m afraid. They’ve secured themselves against the world and are in the process of transforming themselves. That very transformation is happening all around you right now. Thousands of moths and butterflies are re-inventing themselves in our woods and green spaces ready to dazzle us with their beauty next year. I hate to say it again, but what a way to make me feel unproductive – it doesn’t matter how many months I lie in bed, I’m never going to grow wings.