Pirated pupas of the Common Banded Awl
On 18 July 2007, I visited Kumargram, a tea-garden, just a handful of kilometers South of the Bhutan border and a few kilometers West of the Sankosh river, the natural feature which separates the West Bengal Dooars from those of Assam.
Nearby was a disused World War II airstrip amidst a tea-garden. I took the opportunity to rummage around during my lunch-break.
While I was there, I noticed a small tree with leaves and branches coming down to my shoulder height. The leaves were jigsaw shaped; something had been at them. Again and again, I found leaves folded to form narrow open tubes held together with a few strands of a fibre.
In each leaf-tube was the remains of a pupa. The pupas were brown, sometimes with green slimy-looking markings. These pupas were more or less heavily covered with a white powder, which I then thought was that of a fungus. The pupas had holes in them – some had large holes at the head indicating the point of exit of a newly hatched butterfly, others with smaller holes at the sides or on the back, the likely exit point of a newly hatched parasite such as a wasp.
I looked around for the butterfly whose pupas it could be, and almost immediately, I saw a handsome robust skipper with large antenna hooked elegantly and ending in sharp points. The head had fine greenish bristles. The forewings were triangular, held straight back and half-covered by well-rounded hindwings. The hindwings had a thin clear white band which was diffused towards the outer side, the distinctive feature of the butterfly. There were four or five of these handsome skippers, buzzing strongly around the bush and settling for short periods of time on exposed leaves or twigs.
I found one perched low, which allowed me to catch him gently between my thumb and forefinger. Knowing that hesperiids require both UP and UN images, I opened its wings for photography, but the best of efforts could not prevent some smearing off of the scales.
Strangely, the UP was a featureless brown. Later on I referred to Wynter-Blyth and Kunte and concluded that it later as the COMMON BANDED AWL, (Hasora chromus). I also found out that the white powder on the pupas was a characteristic of the subfamily Coeliadinae or the Awls.
The butterfly, when released, showed no inclination of flying off, allowing some excellent shots of it on my hairy arm! When I had had my fill of photographing the skipper, I shooed it off my hand. It then resumed flying around, looking, I thought, for some suitable leaves on which, I presumed, to lay eggs.
Now seeing the dismal pupal casts, I looked around for a wasp which could have been the brood-parasite. I soon saw a small, blue-coloured wasp, buzzing lazily along with legs suspended below it.
This I suspected may be the culprit, but I had no net to catch it and it did not settle for me to get a photograph. Anyway, it could have been flying along there by coincidence. The only way to confirm whether this was the wasp predator is by examining parasites emerging from a pupa or by actually observing a wasp piercing a pupa with its ovipositor. I anyway had no more time to spare and reluctantly left the spot.