As we walked through the Hollongapar sanctuary, I saw several of the common birdwings (Troides helena). These are distinctive large black and yellow butterflies which usually fly fairly high but below the canopy of the forest. I’d first seen them several years back somewhat further south, in Tripura. Its range continues south and east from Nepal into the Indonesian archipelago. It is so distinctive, that I had no trouble recalling its name. I had seen a mating dance once, but this time I saw them only singly.
T. helena gets its colour from pigments, unlike many common butterflies in which diffraction of light plays a part. The strong colour advertises the fact that it is poisonous. Usually in butterflies most of the eating is done by the caterpillar (larva), so that the adult (imago) can spend its time flitting from flower to partner and so on. The poison is obtained by the larva from some of its food plants. I was surprised to find that it is fairly long-lived for a butterfly: the larval stage lasts for three to four weeks, then it pupates for about two weeks, and the adult can live as long as six weeks.
All morning we’d seen these butterflies. After lunch near the forest guest house, I walked back along one of the forest paths to see whether I could spot any more butterflies. The Lotus stayed behind near the guest house. When I returned disgruntled from a failed search, she had the wonderful shot which you see as the featured photo. This individual looks like a male. What a wonderful piece of serendipity, and what a lovely picture. The Lotus was kind enough to give me the photo for my use in this post; if you like it, please leave a note which I can pass on.