At 140 mm across the Orchard Swallowtail, or Large Citrus Butterfly (Papilio aegeus) is by far the largest butterfly in southern Australia, especially in the Strathbogies. When the caterpillar turns into a chrysalis (the name given to pupating butterflies), it not only undergoes a complete change of shape, colour also changes so that the defenseless chrysalis is camouflaged.
And the colour of the chrysalis varies, depending on where on the plant its attached.
The above chrysalis has taken on the shape and colour of a branch, or stem (click the photo to look more closely). However, if the chrysalis pupates among leaves, it looks quite different to the above – in fact it looks very much like a curled leaf. See also how the chrysalis is suspended in a silk harness that’s attached to the branch. The base of the chrysalis is also attached to the branch, by a fine web of silk.
Now for a glimpse of the process. We start off with a fully-grown caterpillar and end with a spectacular butterfly – one of the true wonders of evolution! It takes the caterpillar several days to become a chrysalis, then several more weeks, or longer in cold weather, to metamorphose and emerge as a butterfly. There are photos of earlier-stage caterpillars on this earlier post. The final change from pupating caterpillar to chrysalis occurred during the night (in this instance) and while I wasn’t watching (damn). The adult butterfly had just emerged and was letting its wings dry and harden. The fine scales that coat the butterfly’s body and wings and give it colour, can clearly be seen on the fresh, still perfect, male Orchard Swallowtail, below.
To see how the caterpillar amazingly turns into the pupa (chrysalis), view this lovely YouTube clip.