Butterflies of
Thailand, Malaysia &
Borneo
Horsfield's Darkie
Allotinus horsfieldi permagnus
FRUHSTORFER, 1913
Family - LYCAENIDAE
subfamily -
MILETINAE
Tribe - MILETINI
introduction
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habitats |
lifecycle |
adult behaviour
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Horsfield's
Darkie Allotinus horsfieldi permagnus,
Tapah hills, West Malaysia |
Introduction
Horsfield's Darkie is one
of several very similar species in the tribe Miletini, which are
characterised by having attractively mottled and striated patterns on their
underside wings, a long thin abdomen, a very long proboscis, and erect labial
palpi.
The
butterfly is elusive but fairly common in the lowland rainforests of peninsular Malaysia, Sumatra and
Borneo. Closely related species occur throughout the Oriental region - some of
these are very
widespread, whilst others are endemic to particular islands or restricted
altitudinally.
In
common with all other members of the subfamily Miletinae, this species is
entirely aphytophagous, meaning it feeds carnivorously, parasitically, or on animal
by-products.
A
great deal remains to be learnt about the ecology of the Miletinae. It is known
that the adults and larvae of most species live in association with ants, and
that most feed parasitically or carnivorously on Homoptera ( aphids, coccids,
psyllids and membracids ). It is probable that all Miletinae species are
involved in complex 3-way symbiotic relationships with ants and Homoptera.
Habitats
Tropical dipterocarp rainforests at altitudes below about 300 metres. Other
related and very similar species can be found at much higher altitudes. In my
experience this species is usually found close to rivers, or in seasonally
inundated forest.
Lifecycle
The butterflies are continuously brooded and can be found in
roughly equal numbers at all times of year.
The eggs are laid amidst
clusters of membracids ( tiny aphid-like creatures ).
The larvae are adorned with rows of spiky humps on the back and sides. Unlike
most lepidopteran larvae they do not eat plant matter, but feed parasitically on
membracids during their early instars. When old enough and big enough they
devour complete membracids.
The larvae of the closely related genus
Spalgis
feed on coccids, while
Logania
feed on aphids. At least one
Allotinus
species,
apries,
feeds on coccids when it is tiny. When it reaches the 2nd instar it develops
protrusions that are used as grapples by the ant
Myrmecaria lutea
to carry it to it's nest - where the larva proceeds to devour the ant grubs.
Details of the pupal stage are unknown, but it is likely that pupation
takes place within ant nests.
Adult behaviour
The butterflies are sedentary in behaviour, and semi-crepuscular
in nature, becoming active just before dusk, although in dull
weather conditions they may fly earlier in the day. The flight is
weak, and only very short distances are covered.
They are normally
encountered solitarily, or in very low numbers, and can be seen at
rest on the foliage of bushes in the undergrowth, usually in the
darkest recesses of the rainforest. Males perch on foliage at a
height of about 1 metre, and use these vantage points to await
passing females. Often 2 or 3 males will be found in close
proximity - when males meet they chase each other rapidly back and
forth until one or the other submits to bullying and flies away.
In August 2004,
when exploring Mulu national park in Sarawak, I found a specimen
of Allotinus horsfieldi
feeding in company with ants and membracids. The membracids were
piercing plant stems to fed on the sap, and were being "milked" by
the ants, to obtain a sweet secretion. The butterfly, which was
totally ignored by the ants and their "herd", spent several
minutes with it's long proboscis out-stretched, imbibing the
secretion directly from the backs of the membracids.
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