Parasa lepida, the Blue-streaked Nettle Grub: 6. Pupa

on 18th November 2016

BSNettleGrub-pupating 1524h 201016 [wyc]

An early indication of pupating is when the Blue-streaked Nettle Grub (Parasa lepida) moves around aimlessly LINK. Subsequently its dorsal blue stripe turns dark, followed by the rest of the body (above: pupating grub on right). It stops eating and may either discharge a black liquid that stains the leaf surface (below). Others may discharge a larger than normal black pellet. Should this pellet lands in water it may partially dissolve giving a localised black stain.

BSNettleGrub-black discharge 1800h 121016 [wyc]

It returns to the branch or the underside of a leaf to spin a cocoon before pupating (below).

BSNettleCrub-pre-pupa 151016 0518h [wyc]

This was usually seen in the late evening, continuing through the night to complete the cocoon by the early hours of the next morning (below).

BSNettleCrub-pupa 150916 0922h [wyc]

Only then will it form the thick oval pupal covering that is about 12-15×7-10 mm (below).

Scale in mm.
Scale in mm.

The entire process of cocoon formation can be seen in the video below.

In nature the cocoon is reported to be found buried in the soil or among leaf litter. However, I did come across one cocoon attached to the underside of a leaf in the garden. In my observations, the cocoons were attached to the underside of a leaf except one attached to the twig. This can be because the grubs were confined to the leafy twigs by a water barrier.

YC Wee
Singapore
31st 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.

Other posts by YC Wee

Leave a Reply

Your email address will not be published. Required fields are marked *

Categories
Archives

Overall visits (since 2005)

Clustrmaps (since 2016)