The World of Birdwing Butterflies

SCHOENBERGIA MERIDIONALIS

IUCN conservation status category: VULNERABLE.

Schoenbergia meridionalis is the smallest of the Ornithoptera group of birdwing butterflies. The underwings of the male are so small that it is said to be a bad flier, only fluttering weakly from tree to tree unless being disturbed.

The males are said to enjoy the lights of the canopy, rarely coming down to ground. Mr Jan Pasternak (1981), however, claims this is not correct, saying that the males are so poor flyers that they occupy the lower levels of the forest, usually being seen at elevations only two or three metres above the ground.

The females will usually fly at much higher altitudes than the males, but often descend to ground and is therefore more frequently collected. Ray Straatman, nevertheless, proved the sex-ratio to be nearly equal (op cit Haugum & Low, 1979).

Ovipositing takes place on plants in the flatlands, never in slopy terrain. The ovum is more than 3 mm in diameter, a remarkable size considering the small body of the female. The female usually carries only 5-7 eggs at a time. The eggs seem to be vulnerable to parasitic flies; 50-60% being attacked in the Kamrau Bay populations (Pasternak, 1981) .

Until fairly recently, the only known populations of meridionalis were in the south-eastern lowlands of Papua New Guinea, in addition to the little-known Nomnangihé population in Irian Jaya.

But during expeditions  in 1978, 1979 and 1980 Mr Jan Pasternak also found meridionalis in the Kamrau Bay area, 200 km west of the Weyland Mountains in western Irian Jaya.

In PNG it was previously assumed that paradisea and meridionalis divided the country between them, with paradisea inhabiting the areas north of the highlands while meridionalis ruled south of the mountains. But meridionalis has now been reported from the Southern Highlands and East Sepic provinces. My figured male was in fact collected in the Aseki subdistrict, Morobe Province. Nevertheless, meridionalis is a rare and vulnerable species.

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