Butterflies of
Thailand, Malaysia &
Borneo
Eumolphus Oakblue
Arhopala eumolphus
CRAMER, 1780
Family - LYCAENIDAE
subfamily -
THECLINAE
Tribe - ARHOPALINI
introduction
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habitats |
lifecycle |
adult behaviour
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Arhopala eumolphus,
female, Ulu Gerok,
West Malaysia |
Introduction
Entomologists disagree about how many species should be placed
in the genus Arhopala - Evans for
example considered that the genus should only include a small
number of Papuan butterflies, and placed other species in
Narathura,
Aurea and Panchala. Here I
follow the course adopted by Corbet & Pendlebury, who include
all these genera within Arhopala.
Thus defined, the genus is widespread, with various species
found from Afghanistan to Japan, and south across the Pacific
islands to Australia. In total there are over 200 species,
collectively known as Oakblues.
The undersides of all species are earthy brown, and bear a
complicated pattern of dark spots and blotches, edged in
whitish. All Arhopala species have
iridescent green eyes.
Distinguishing the species is very difficult, and best achieved
by reference to the keys and genitalia illustrations in Corbet &
Pendlebury.
In Malaysia
there are at least 110 species,
most of which are some shade of metallic blue or purple on the
upperside, although there are several iridescent green species
including aurea and
trogon.
Arhopala eumolphus is one of
several species which the males are metallic green above, but
the females are blue. It occurs from Myanmar to Java.
Habitats
This species is one of the commoner Oakblues in peninsular
Malaysia, and occurs in primary forest habitats at altitudes
between sea level and about 600m.
Lifecycle
The lifecycle has been studied, but the larval foodplant has not
been identified. Arhopala species
use a wide variety of foodplants including
Quercus ( Fagaceae ), and various species of
Myrtaceae,
Combretaceae and Lythraceae.
The egg is laid singly on the underside of a mature leaf, and is
white, with a reticulated network of ridges. Often several eggs
can be found on one leaf, probably laid by the same returning
female.
The caterpillar hatches after about 2 or 3 days, and partially
eats its eggshell before moving away to find a fresh young leaf,
in which it nibbles tiny holes. When fully grown it is oval in
shape, slightly flattened, and pale translucent green in colour
with a prominent creamy dorsal line. It is attended by the ant
Polyrachis which milks it to obtain
sweet secretions exuded from it's dorsal honey gland.
The chrysalis
is formed on the underside of a leaf, and is pale brown,
speckled with dark olive dots.
Adult behaviour
Oakblues of
both sexes tend to spend most of their time sitting motionless
on the foliage of trees and bushes, at a height of about 2 - 5
metres. They are not known to visit flowers, and males do not
appear to come to the ground to imbibe mineralised moisture. It
seems likely that both sexes obtain their sustenance from aphid
secretions on leaves and twigs.
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