Autumn Leaf butterfly: 2. Caterpillar pupating

on 15th January 2016

A few of the mid-December 2015 Autumn Leaf (Doleschallia bisaltide) caterpillars, courtesy of Maryann Vitudio, showed signs of pupating within days. They were moving up and down the stems of Common Asystasia (Asystasia gangetica) grown in potted soil placed in a basin of water. They even wandered around the rim of the pot – see HERE

I find the change from an active caterpillar to a passive pupa fascinating.

Once the caterpillar is satisfied with a particular spot, either on the underside of a twig or of a leaf, it weaves a tiny silk pad on the surface. And using its pair of anal claspers, it attaches itself firmly onto it, hanging head down with the anterior end pointing upwards in a “J” shape (above)

The pupating caterpillar shows slight movements as the body begins to transform into a pupa (below). The pupa is formed under the skin of the caterpillar and when the transformation is complete, the skin splits near the head end to expose part of the newly formed, whitish pupa (video above).

There is violent wriggling as the old skin is gradually pushed up the body of the newly formed pupa until it gathers as a crumpled mass at the point of its attachment and then discarded (below). This takes up to 3-4 minutes.

Around this time numerous microscopic hooks develop to firmly anchor the pupa to the silk pad. This is to ensure that the pupa does not get detached with its violent movements to discard the old skin. Once the skin is detached, there is a further 4-5 minutes of movements as the pupa wriggles, twists and turns before it settles down (video below).

The pupa then hangs passively for the next 8 days. It will only wriggle about when disturbed.

YC Wee & Maryann Vitudio
December 2015

If you like this post please tap on the Like button at the left bottom of page. Any views and opinions expressed in this article are solely those of the authors/contributors, and are not endorsed by the Lee Kong Chian Natural History Museum (LKCNHM, NUS) or its affiliated institutions. Readers are encouraged to use their discretion before making any decisions or judgements based on the information presented.

YC Wee

Dr Wee played a significant role as a green advocate in Singapore through his extensive involvement in various organizations and committees: as Secretary and Chairman for the Malayan Nature Society (Singapore Branch), and with the Nature Society (Singapore) as founding President (1978-1995). He has also served in the Nature Reserve Board (1987-1989), Nature Reserves Committee (1990-1996), National Council on the Environment/Singapore Environment Council (1992-1996), Work-Group on Nature Conservation (1992) and Inter-Varsity Council on the Environment (1995-1997). He is Patron of the Singapore Gardening Society and was appointed Honorary Museum Associate of the Lee Kong Chian Natural History Museum (LKCNHM) in 2012. In 2005, Dr Wee started the Bird Ecology Study Group. With more than 6,000 entries, the website has become a valuable resource consulted by students, birdwatchers and researchers locally and internationally. The views and opinions expressed in this article are his own, and do not represent those of LKCNHM, the National University of Singapore or its affiliated institutions.

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