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Text and photographs protected by Copyright © Adrian Hoskins 2007, and must not be published in part or in whole elsewhere without prior written permission from the author.
Butterflies of Malaysia and Borneo
 
Horsfield's Darkie
Allotinus horsfieldi permagnus FRUHSTORFER, 1913
Family - LYCAENIDAE
subfamily - MILETINAE
Tribe - MILETINI
 
 introduction | habitats | lifecycle | adult behaviour
 
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, all of which are characterised by having attractively mottled and striated patterns on the underside wings, a long thin abdomen, a very long proboscis, and erect labial palpi.
 
The butterfly is frequent in the rainforests of peninsular Malaysia, Sumatra and Borneo. Related species occur throughout the Oriental region, some being 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 - feeding 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, A. apries, feeds on coccids when it is tiny, but during the 2nd instar the larva develops protrusions which act as grapples used by a particular species of 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 as yet 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.

 

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.

 
                                                        
In common with most other butterflies in Malaysia, Borneo and Palawan, the habitats of this species are severely endangered. Rainforest only remains on the steepest mountain-sides, and at a small number of nature reserves. Many of the reserves are now threatened with reclassification and subsequent exploitation at the hands of major international companies.
 
Tragically, the huge areas of tropical rainforest which once covered the lowlands of West Malaysia, Sabah and Sarawak have been almost entirely cleared, with only a few "islands" of original forest remaining, surrounded by vast oil palm plantations.
 
The forests of Kalimantan ( the Indonesian sector of Borneo ) have suffered a similar fate, and what little remains is now under severe threat,
as the protected status of nature reserves is being revoked to make way for concession areas that will be subjected to open cast coal mines, logging, and clearance for immense oil palm plantations to satisfy the demand for bio-diesel fuel.
 
The extent of the devastation is immense, and the consequences catastrophic, not only for butterflies, but also for orang-utans, proboscis monkeys, hornbills, and myriads of other mammals, birds, amphibians, reptiles and insects - our natural heritage is being annihilated.
 
You can help prevent further devastation - please lobby your governments, and contact the rainforest conservation organisations who organise on-line petitions and use scientific evidence to apply pressure to the governments of Malaysia and Indonesia to halt the devastation.
 
 
Text and photographs protected by Copyright © Adrian Hoskins 2007-2008, and must not be reproduced or published in part or in whole elsewhere in any form without written permission from Adrian Hoskins. Breach of copyright will be pursued by litigation.
 
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