A couple of weeks ago I got a batch of tiny, newly hatched Swallowtail caterpillars sent to me by a specialist breeder. I blogged about them here - they were too small to photograph easily, despite me using a macro lens to do it. They were only a couple of millimetres long.

Now look at them! The largest of them is easily 40 millimetres. That to my mind is an amazing amount of growth in just 14 days! It hasn't been success all the way, I started out with 10 larva - 7 remain and they seem to enjoy their diet of fennel, although I understand they are partial to most Umbelliferae, I haven't been brave enough to try them on any of fennel's relatives.

I think if they continue to grow at this rate, it would be about 4 weeks before they get to their optimum size to go through the next stage of their metamorphosis, and change into Pupae.

One thing I learnt during the past 2 weeks, is that, as they grow, they shed their skins. They also seem to change quite a lot in other ways. The colours are much more vibrant now, and the little hairy barbs they had as tiny larva, seem to have disappeared. Another feature they seem to have acquired is quite bizarre and I only noticed it by accident when replenishing food. I needed to move one of the large caterpillars from its perch onto the new foliage. I had used a soft water colour brush for this initially, as they were too delicate to handle. Now I just trim the old foliage around the caterpillar away and then place it on the new food plant. In doing this  the last few days, if I am not extremely careful, it  to rears up, and from its head a bright orange 'thing' appears. It's forked like a snakes tongue and pops out and then disappears!   I am not sure what it is called, but I suspect it is intended to scare off any would be predator.

So perhaps in a couple of weeks they will start turning into Pupae and begin the final stage of their transformation into a beautiful butterfly.