The region of New Guinea is renowned for the beauty, size and variety of its insects and, in particular, its butterflies. Especially well-known among naturalists, entomologists and collectors are the magnificent birdwing butterflies which are only found in this region of the world.
Papua New Guinea is home to more than 700 different species of butterflies. This is more than two times the number of species found in the continent of Europe which is about six times larger than PNG. The reason for this diversity of butterflies and insects in general is the tropical climate and the mountainous topography.
The many mountains valleys and islands not only offer a variety of different habitats but also lead to the evolution of many new species which are peculiar to Papua New Guinea and are sometimes only found in a restricted area. One example are many of the Delias species which are only found on certain mountain peaks, another is the largest butterfly of the world, Queen Alexandra's birdwing (ornithoptera alexandrae) which is confined to the lowland rainforest of the Popondetta region in Oro Province.
Other spectacular examples of Papua New Guinea's insect fauna include the Hercules Moth (Coscinocera Hercules) which is the largest moth in the world, or one of the largest stick insects in the world, Eurycnema Goliath.
The caterpillars of butterflies feed on many specific foodplants, some of them poisonous to large animals like the milkweeds or the alkaloid-rich Aristolochia vines which represent the food plants of the birdwing caterpillars. Storage of these poisons provides these caterpillars with protection against predators and sometimes even makes the adult butterflies distasteful to birds. Many of these butterflies have bright aposematic colouration to warn potential predators of their bitter taste.
Palatable species sometimes copy these colourations to trick predators and gain some protection for themselves (like the blue day-flying moth Alcides agathyrus w which is though to copy the swallowtail Papilio laglaizei) whereas other species (like the leaf-like coloured Doleschallia) prefer a cryptic appearance to escape their enemies.
Although different species of butterflies have developed various strategies to escape their many predators and parasites or to adapt to changing conditions of their environment, their survival is easily threatened by destruction of their natural habitats, in particular the rainforests, through human activities. An example is the rare Queen Alexandra's birdwing which is endangered by logging operations and agricultural clearing of the rainforest. Fortunately this species is now the subject of a conservation programme which hopefully will ensure its survival.