Butterflies of
Thailand, Malaysia & Borneo
Lemon Emigrant
Catopsilia pomona
FABRICIUS, 1775
Family - PIERIDAE
subfamily -
COLIADINAE
Tribe -
introduction
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habitats |
lifecycle |
adult behaviour
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Catopsilia pomona pomona
f.
catilla,
female, Taman Negara, West Malaysia |
Introduction
There are 6 species
in the genus Catopsilia, including
gorgophone from Australia,
thauruma from Madagascar;
pyranthe and
scylla from the Oriental region; and
florella which is found all across
Africa and also in India, Myanmar, Thailand and east to China.
Catopsilia pomona is distributed
from Sikkim to Malaysia, east to the Philippines, and south
through the islands of the South Pacific to Australia, where it
is very widespread.
Early
entomologists considered Catopsilia pomona
and Catopsilia crocale to be
separate species, but it is now scientifically proven that both
are forms of the same subspecies - C.
pomona pomona.
There are in fact at least 6 different colour forms or "morphs", 3 of which are illustrated
here.
The various "pomona" forms all have
a pair of silvery spots on the underside, in the cell of the
hind wing, and often have dark patches, these being most
pronounced in f. catilla. Another
characteristic of the pomona forms
is that the upper surfaces of the antennae are reddish. On the
upper surface the wings are whitish with a deep yellow flush in
the basal area ( f. hilaria ), or
plain creamy white in other pomona
forms, always with a thin black apical border. The various "crocale"
forms on the other hand have black antennae, and their wings are
unmarked on the underside.
Captive rearing experiments by Yata & Tanaka have demonstrated
that each of the various forms can be induced by controlling
photoperiod and temperature during the larval stage, indicating
that weather and time of year are influencing factors. It may
seem odd therefore that the 3 specimens illustrated here were
all photographed at the same location in Taman Negara, on the
same day - 12th May - and that they all appear to be freshly
emerged. The logical conclusion is that the eggs were laid at
different times, and that some of the resulting larvae developed
rapidly and others much more slowly, thereby producing different
adult forms which all emerged at the same time.
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Catopsilia pomona pomona,
male, f.
hilaria ( left
),
pomona crocale f.
alcmeone ( right ) |
Habitats
This species is ubiquitous, being found throughout the year in
open areas in secondary forest, along river courses, on open
grassland, and even in the hot arid deserts of outback
Australia. In Malaysia it occurs at altitudes between sea level
and at least 800 metres.
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Catopsilia pomona crocale, f.
alcmeone |
Lifecycle
The tall elliptical eggs are yellow and vertically ribbed. They
are laid singly or in small batches on the foodplants.
The caterpillar
when fully grown produces 2 morphs, one being yellowish green peppered with tiny black
dots, and the other being pale yellowish brown. Both forms have a broad black stripe along the side, below which
is a slightly narrower cream stripe. It feeds diurnally on many
trees, shrubs and herbaceous plants in the
Leguminosae ( Fabaceae ), favouring Cassia
but also using
Butea,
Bauhinia, Pterocarpus,
Senna and
Sesbania.
The chrysalis
is of the typical Pierid shape, pale green in colour, with a
thin yellow line along the sides and a blue-green line along the
back. It is attached by the cremaster and a silken girdle to the
underside of a leaf, or to a stem.
Adult behaviour
The butterflies
are strongly migratory in habit, and can be seen flying in
undulating "strings" of a dozen or so adults, travelling up and
down the rivers which they use as migration corridors linking
their high and low elevation breeding sites. During these
migrations both sexes, but especially the males, can be observed
congregating in large groups on sunlit riverbanks and sandbars
where they settle for long periods to imbibe mineralised
moisture.
Both sexes also commonly visit flowers including
Lantana,
Jatropha and Catunaregam.
Catopsilia pomona
female, Darjeeling, India
( image
© Haraprasan Nayak )
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