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LIFE HISTORY OF THE TAMIL YEOMAN BUTTERFLY
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Author:  Saman [ Sun Mar 28, 2010 11:21 am ]
Post subject:  LIFE HISTORY OF THE TAMIL YEOMAN BUTTERFLY

Life history of the Tamil Yeoman Butterfly

By Dr. Nayana Wijetilaka
Department of Zoology, Faculty of Science,
University of Peradeniya, Sri Lanka


@ TIGERPAPER: Vol. 36: No. 2 April-June 2009

The Tamil yeoman butterfly (Cirrochroa thais),
first described by Fabricius in 1787, belongs to
the family Nymphalidae which comprises 67 species
in Sri Lanka, including seven endemics (Perera and
Bambaradeniya, 2006.) This is the only member of
the genus Cirrochroa recorded in Sri Lanka, and
the species is restricted to Sri Lanka and India. It is
not an uncommon butterfly, and occurs throughout
the island up to 1,200 meters above sea level. The
Tamil yeoman is a strong butterfly and can fly at
considerably great speeds when threatened and
disturbed; however, the species can be easily
approached while feeding. This species usually flies
up to tree canopy level and can also be seen on wet
patches on the ground, depicting a large microhabitat
selection. Tamil yeoman butterflies breed throughout
the year and the known host plants of the caterpillars
belong to the family Flacourtiaceae, especially
Hydnocarpus wightiana (Davidson & Aitken, 1890).

Image

In August 2007, a Tamil yeoman butterfly was
observed ovipositing on the underside of a leaf of a
Makulu (Hydnocarpus venenata) tree near a river
bank at Doluwa in Kandy district. This is an endemic
plant and grows along water courses in the wet zone
of Sri Lanka. The oviposition site was the underside
of a young leaf, 1.8 m above ground, and shady.
The egg clutch of the species was unusual in form
as the ten eggs were attached to each other in the
shape of a short beaded string. The Tamil yeoman
is the only known butterfly that shows this type of
egg-laying pattern in the country (M. van der
Poorten, pers. comm.). The eggs were originally
yellowish green in color, 1.5x1.5 mm in size and
cylindrical in shape and showed clear longitudinal
ridges, continuing along the egg string.

Image

The egg clutch was removed with the branch from
its original location and kept in a glass container
under optimum conditions. The eggs hatched four
days after laying, but only three hatchlings emerged.
The rest of the eggs may have been unfertilized.
The caterpillars were fed on fresh shoots, young
leaves and young stems of the plant. Feeding was
initiated from the leaf tip and continued towards
the leaf base in an irregular manner. Feeding was
observed randomly during the day time.
The larvae had six rows of uniformly black,
branched, shiny spines, two sets dorsally and two
sets each on the lateral sides. Two black
characteristic spots were present on the yellow
forehead and one on each lateral side of the head.
Along the two sides of the body was a brown stripe
edged below by a white line.

By the 8th day after hatching the larvae were 26
mm in length. They stopped feeding by the 10th
day and were observed actively moving on the
plant, probably searching for a suitable place to
pupate. By the 11th day all three caterpillars were
observed hanging on small silken pads on the
underside of leaves.

Image

By 12.20 hrs of the same day, one caterpillar had
metamorphosed into a bright yellow chrysalis, and
the others did the same a few minutes later. Curved
spine-like projections depicted the locations where
the branched spines were present on the body of
the caterpillar.

Image

Eventually the chrysalises changed colour to dark
brown by the 18th day after hatching.

One week after pupation, three brilliantly colored
imagoes emerged on the same day at 15.10 hrs,
15.24 hrs and 15.36 hrs respectively. They
remained on the same leaves for nearly one and a
half hour until they experienced their first flights.


Image

References
- D’ Abrera, B. 1998. The Butterflies of Ceylon.
Wildlife Heritage Trust, Sri Lanka

- Kolambaarachchi, R. 2000. Notes on the life cycle
of common Mormon (Papilio polytes Linn,
1758). Sri Lanka Naturalist.

- Nanayakkara, S. 2000. Breeding the Common
Grass Yellow Butterfly. Loris 22(2):52-53

-Perera, W.P.N. and C.N.B. Bambaradeniya. 2006.
Species Richness, Distribution and Conservation
Status of Butterflies in Sri Lanka. The fauna of Sri Lanka,
IUCN-The World Conservation Union.

- Woodhouse, L.G.O. 1950. The Butterfly Fauna
of Ceylon. Ceylon Government Press.



Author’s address: Department of Zoology,
Faculty of Science, University of Peradeniya,
Sri Lanka; nayanata at gmail.com

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