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Thalatha
sinens Walker
Orthosia sinens Walker, 1857, List Specimens lepid. Insects Colln Br. Mus., 11:
746.
Thalatha sinens ioleuca Prout, 1928, Bull. Hill. Mus. Witley., 2: 72.
Thalatha sinens Walker;Holloway, 1976: 13.
Diagnosis.
There is
some sexual dimorphism in the hindwing, males having. whitish wings, those of
the female being grey. The forewings in both sexes are white, crossed by pale
grey fasciae, the medial one being broader and connecting with a longitudinal
grey bar posterior to the subtornal black streak. The basal black streak is
reduced or lost, the subtornal one consisting of
a row of two or three black triangles increasing distally, with a short,
separate, marginal streak.
Geographical range. India, Burma, Sumatra (ssp. ioleuca Prout),
Borneo.
Habitat
preference. The
specks is infrequent in Borneo, most specimens being taken in lowland forest.
Two are from 1200m, in an open limestone area on G. Api and a partly cultivated
zone of G. Kinabalu.
Biology.
Bell (MS)
has described the biology. The larva is a similar shape to that of Craniophora
fasciata, cylindrical, tapering to a small head anteriorly over the thorax,
with a slight constriction at T1. The body is chocolate-brown, lighter
ventrally, with primary setae only, white, set on chalazae that are basally
black, apically white. The membrane between the first and second thoracic
segments is pale orange, seen when stretched.
The larva lives on the underside of leaves of seedlings or bushes of the
host-plant within the shade of the forest. It is sluggish, resting with the head
curved round to one side. When disturbed, the head and rear part of the body are
thrown up over the dorsum to touch the middle of the body, the thoracic legs and
mandibles directed upwards, a green juice being emitted from the mouth.
Pupation, as in C. fasciata, is in a cell in rotten wood, closed with a
web of silk containing particles of wood. The larva will bore into any twig
thick enough but often takes advantage of old holes.
The host-plant is Olea (Oleaceae).
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