Butterflies of
Thailand, Malaysia &
Borneo
Wavy Maplet
Chersonesia rahria
MOORE, 1858
Family - NYMPHALIDAE
subfamily -
CYRESTINAE
Tribe - CYRESTINI
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Chersonesia rahria,
male, Taman Negara, West Malaysia ©
Adrian Hoskins |
Introduction
The tiny Maplet butterflies are amongst the most delightful and
interesting rainforest species found in Malaysia, delicately
marked with fine wavy lines on a bright orange ground colour.
There are 7 members of the genus
Chersonesia, all endemic to the Oriental region. They are
very closely related to the Cyrestis
Mapwings, as can be seen by comparing
Chersonesia rahria with the much larger but otherwise
virtually identical Cyrestis thyonneus.
Both sexes of
rahria are similarly patterned, but
the female is slightly paler, with broader and more rounded
wings. The pattern is repeated on the underside of the wings in
more subtle hues.
Chersonesia rahria, in common with
most other members of it's genus is widespread throughout the
Oriental region, being found in West Malaysia, Sumatra, Borneo,
Java, Palawan and Sulawesi.
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Chersonesia rahria,
Taman Negara, West Malaysia ©
Adrian Hoskins |
Habitats
This species breeds in primary rainforest at elevations between
0-800m. At higher altitudes it is
gradually replaced by C. risa, in
which the outer lines on the forewings are straight rather than
wavy.
Lifecycle
The yellowish-green egg is dome-shaped with eleven prominent
vertical ridges. It is laid singly at the edge of a leaf of the
climbing fig Ficus aurantiacea (
and probably other Ficus species ).
Prior to
hatching the larva nibbles an almost complete circular channel
out of the upper part of the eggshell, thereby creating a
trapdoor which it pushes up and out of the way as it emerges.
When small the
larva rests on the underside of a leaf, at the tip. It nibbles
chunks from either side, and sits on the remaining projecting
midrib, pointing inwards, using it as a retreat. At this stage
of its life it often decorates its body with its own droppings,
possibly because the acrid smell deters ants or parasitoid
wasps.
When older the
larva has a habit of biting part way through the midrib. The
most likely explanation for this is that the sap contains
toxins, and that severing the "artery" prevents these from
reaching the part which the caterpillar chooses to eat.
The fully grown
larva is pale green with oblique stripes of darker green. It is
described by Corbet & Pendlebury as being cylindrical and
smooth-skinned, "with a pair of long filamentous processes
on the 2nd and 8th abdominal segments, the former curved
backwards, and the latter forwards, and both serrated on the
posterior edge". The brown head also bears a pair of recurved
horns.
The brown
chrysalis resembles a small dead leaf. Like the larva, it has a
pair of curved horns on the head. There is a small thorn-like
projection on the thorax, and a dorsal keel projecting from the
abdomen. It is suspended by the cremaster from a leaf or twig.
Adult behaviour
The
Chersonesia Maplets are dainty
little butterflies which flit regularly from spot to spot, but
never stray far from their favoured places. They will often
perch momentarily on the underside of a leaf before fluttering
daintily to another leaf nearby, on which they settle with wings
fully outspread and held flat against the surface. At other
times they like to land on the ground, usually on wet leaf
litter, and will spend long periods probing among the rotting
vegetation, at all times keeping their wings outspread.
The butterflies
are commonest in the wet season, and will fly in light rain,
although they are much more active in hot sunny weather
conditions, at which time they can be found in wet parts of the
forest, flying in places where dappled sunlight filters through
the trees.
I have never
seen either sex visit flowers - both sexes seem to obtain their
sustenance either from mineralised moisture on the ground, or
from aphid secretions ( and possibly bird droppings ) on the
surface of leaves. It is notable however that the closely
related Cyrestis Mapwings often
visit fungi, and while I have never seen them doing so,
Chersonesia are quite likely to
behave similarly.
Unlike most
butterflies which roost with their wings held erect, Maplets
hide overnight or on rainy days beneath leaves, with their wings
fully outspread - another feature they share with their
relatives in the genus Cyrestis.
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