While walking through the Hollongapar Gibbon Sanctuary, I kept seeing a bright orange, blue and black butterfly flitting just under the lower canopy. It was a good flyer, and kept disappearing into the darkness beyond the paths we were following. Mandar claims that he doesn’t know butterflies, but he manages to give a good imitation of an expert. He said immediately that this was an Orange Oakleaf (Kallima inachus).
This was my first sighting of this widespread flyer. Its range extends from Jammu and Kashmir east to Arunachal Pradesh and the other states of north-eastern India along the foothills of the Himalayas. It is also found in central India and the Western Ghats. Mandar was keeping a close look at one while it flew, and so noticed when it came to rest on the trunk of a tree. At rest it is perfectly camouflaged as a leaf. A bird had clearly taken a bite out of the wings of this one.
Very few things can fly with half of its wings gone. If you look at a butterfly carefully, you’ll see that its muscles drive only the front wings; the back wings are usually just loosely attached to the pair in front. The larger surface area of the paired wings allows the maneuverability needed to evade predators. Laboratory studies have shown that butterflies can continue to fly without their hindwings; they just become a little slower. This study also has an interesting bit of speculation about why day-flying butterflies and moths are often brightly coloured.
I haven’t seen a butterfly which is missing bits out of its front wings. I suppose they just can’t fly without them. If a bird gets a bite out of the forewing, then the butterfly just falls out of the air and the bird can just pick it up. It would be interesting to keep watch for a photo of a butterfly with part of its forewings gone.