Change for caterpillars …

From Alwyn. I am attempting to rear four Orange Tip caterpillars all the way to butterflies. The caterpillars undergo a total of five instars (moulting stages) before forming a pupa or chrysalis. They stay in this form for 10 months until next April/May before the adult butterflies emerge. So a long wait!

The process starts when the fifth instar caterpillar, about 31mm long, assumes the pupating position (curved bow-like) on a selected plant stem. A silken thread girdle is spun around its abdomen centre which holds it in place, rather like a rock climbers’ rope. The tail end is attached by small hooks (cremasters) to a silk pad for final stability. It stays like this, motionless for up to 24 hours before the transformation into a chrysalis begins.

The transformation starts with a bump growing on the caterpillar’s head, which quickly develops into a ‘pixie-like’ pointed cap. Then the chrysalis shell seems to envelop the caterpillar from head downward fattening out in the middle (to accommodate the wings?) and continues down the abdomen to the tail end. A little writhing and wriggling dislodges and discards the headpart and the chrysalis is formed: a lovely, elegant ‘gondola’ boat shape form with two pointed ends and a triangular middle area, still attached firmly to the stem. Here is the transformation process sequence, utilising photos from two different caterpillars


Yes a long wait for 10 months before the adult butterflies emerge next April/May.

Very satisfying though to watch the process of how the chrysalis forms. Alwyn.

See more in the comments on this post …

One thought on “Change for caterpillars …”

  1. So what happened to the four little caterpillars? …:
    One caterpillar wandered off. AWOL and never seen again. [I observed one cover almost 6 inches in as many seconds, which is quite a speed for such a little caterpillar. No wonder it wandered out of sight. These ‘walkabouts’ are normal, as the caterpillar goes off in search of a suitable stem on which to pupate.]

    One successfully changed overnight and I missed seeing it!

    One started changing when it was nearly dark (to avoid predators and photographers?). The caterpillar should shake off and discard the unwanted head part but this particular caterpillar couldn’t do it, despite much energetic writhing and wriggling until it finally stopped exhausted. However it survived with a less than perfect chrysalis.

    And finally, the third and last of the caterpillars decided it was time to pupate and also chose the inconsiderate time of near darkness. But thrilling to witness.

    So I now have three chrysalises, two perfect ones and one less so. Unfortunately I will now have to wait 10 months until next April/May before the adult Orange Tips hopefully will emerge. I hope that they all succeed. What a special, exciting and terrific drama and experience. It beats the telly! Alwyn.

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