Parasa lepida, the Blue-streaked nettle grub: 5. Pre-pupating restlessness

on 15th November 2016

When the Blue-streaked nettle grub (Parasa lepida) is about to pupate, it becomes restless. It moves away from its food plant. This is usual among butterflies and moths where the larvae move in different directions to pupate. This is a strategy to increase survival of the species as pupating together can lead to the entire population being wiped out by predators or parasitoids.

BSNettleGrub-pre pupa wandering [wyc]

Thus grubs under observations need to be kept inside a closed container or isolated by a water barrier. In the case of the latter, a small bottle filled with water is used with the branch where the grubs are feeding inserted through the cap. The bottle is then placed in a basin of water. The water barrier ensures the grubs do not wander off and disappear.

BSNettleGrub-pre pupa wandering [wyc]

The pre-pupating grubs will then wander along the branch, to eventually end up around the container (top). In such a situation the grubs will try to cross the water barrier. If there are floating debris, the grubs will use them to escape (above). A video of the movement can be viewed below.

YC Wee
25th October 2016

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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