Ornithoptera alexandrae has the greatest wingspan of any butterfly, with large females reaching roughly 25 centimetres. Its entire known range covers only a few hundred square kilometres of lowland and hill forest in Oro Province, eastern Papua New Guinea, on soils derived from volcanic ash.
That concentration is the species' central vulnerability. In 1951 Mount Lamington erupted violently, devastating a substantial portion of the butterfly's habitat and killing thousands of people. The forest has regenerated unevenly since. More recent losses come from conversion of lowland forest to oil palm and other agriculture, which removes both the canopy the adults use and the Pararistolochia vines the larvae require.
The species was among the first insects listed on CITES Appendix I, and international commercial trade in wild specimens is prohibited. It is often described as the most valuable butterfly on the black market, but specific price claims circulate without verifiable sourcing and should be treated cautiously. Population estimates remain rough because the adults spend much time in the canopy.