Metamorphosing into chrysalides 


A Tailed Emperor Charaxes sempronius Caterpillar curls up in preparation for metamorphosing into a chrysalis - the final stage before it then metamorphoses into an adult butterfly. (See the previous posts for further details on my watch of these caterpillars)


I counted seven caterpillars on the host food plant, a Persian Silk Tree, and as I watching them over the days, I noticed that the first had disappeared a few days ago. So I traced the branches, looking for any wanderers. I first found one crawling swiftly along a branch, heading away from the leaves where it had grown, and probably where its egg had been laid. I measured its pace and was surprised that it was travelling at 20 m per hour. Not bad for a 6 cm long caterpillar. This is probably the most vulnerable stage in its life as it was exposed, with no camouflage while on the bare branches and predatory birds could easily spot it if I could. I found three, and one was still feeding, so where were the other three. Had they found a secluded spot or had they been eaten?


Once they had selected a suitable spot to settle, they fixed themselves by the a specialised hooked organ, called a cremaster at their tail end, to a silk pad they prepare on a branch. Then they hung down on it, and kept wriggling in a curled position to begin with.

Hours later, they let themselves go and hung down straight. This is when they begin to metamorphose.


However - all three of the ones I could find changed into their chrysalides overnight. I set up a slow-motion camera on two of them, but that only worked in daylight. By morning the chrysalides were almost fully formed. The shot above was taken late in the evening. The shot below, of the same animal, was taken next morning. The leaves of the tree close up at night and open by day.


The chrysalis forms inside the old skin of the caterpillar, and when ready, it breaks through the back of the skin. The old skin is then wriggled up to the tail end where it dries and is shaken off. All is complete. I shall now wait about two weeks and try to capture the emergence of one of the butterflies from a chrysalis in slow-motion time-lapse.

Tailed Emperor Caterpillars

As summer has warmed up and butterflies have become more abundant in the garden I have been watching for Tailed Emperor Charaxes sempronius females visiting or laying eggs on the Persian Silk Tree in the garden. I found a hatched butterfly there last year, so wanted to see any caterpillars.

See: the adult here

I haven't seen any butterflies yet this year, but at least one has laid eggs while I wasn't watching. I found chewed leaves the other day and I have been out at night watching the caterpillars since. They are mostly nocturnal feeders. Although I did see one feeding at about 1100 hr one day.


There are six of these caterpillars on the tree at the moment and they are all at this large stage. I never noticed any chewed leaves when they were small yellow instars.


There are many species of caterpillar which adopt defensive postures, curl up, or drop off their branch whenever they are approached by a potential predator, like me, but these didn't do that. They simply carried on eating or walking along a branch while I watched them. The four pairs of prolegs on the abdomen can be clearly seen in this photograph, with the pair of claspers on the last tail segment. The prolegs have tiny, tiny hooks on their tips for hanging onto vegetation.


Their heads are adorned with these marvelous horns. I watched an ant wander close to one and it faced it off, presenting its horned head-plate at the ant, tracing its path as it passed. Not that the ant probably noticed, they follow scents more than vision. But the horns might deter bird predators. And what are those two little horns in the centre. Anyone know?


In this photograph one pair of the true legs on the thorax can be clearly seen, they are segmented with little claws on the end. This caterpillar carried on munching as I clicked away, its mandibles chomping sideways at the leaf with quite astonishing speed and efficiency.

Once they have fed enough, they crawl back along their branches to pre-formed beds. These are silken pads spread on a leaf, or used to hold two or three leaves together. The silk is sticky, and firm on the leaf, and the caterpillars can hold onto it easily. This is important to help the caterpillars stay attached to the leaf when the wind blows. For they certainly bounced about one windy day when I was watching them. They held on effortlessly.



And there they sleep and grow for much of the rest of the night and most of the day, curled up safely camouflaged and with a firm grip of their leaf bed. Isn't it amazing what goes on in the garden.