The beetle which changed colours

One comes across the wonders of natures almost accidentally. In June 2006, on the thirteenth to be precise, my son Aashay and I had driven along the Pokaran – Jaisalmer road to look at Tawny Eagles, who are easily found every few hundred metres perched on the wires or poles. On the way back, we stopped to say hello to a local acquaintance. He stood at his present place of labour, a dolomite mine the concession of which he had taken. The mine, near Chacha village, some 20 odd kms from Pokaran, consisted of an area approx 200 yards in diameter in the middle of which there was a large pit some ten yards across and about ten feet deep. Inside, the pit had tunnels leading from the sides which my friend claimed were quite long and winding and undermined almost all the area of the mine. On the surface, occasional holes with large piles of white dolomite stones around the entrances hinted at the warren below.

The dolomite quarry where we found the beetle.

The dolomite quarry where we found the beetle.

As fathers are prone to do, conversations turn to worldly matters or ‘shop’ so Aashay went wandering around the mine. A fatherly warning followed Aashay that he should stick to the beaten tracks only.

Fifteen minutes later, I walked upto Aashay to fetch him. It was 8.30 and time that we made our way back home for breakfast. Aashay was bent over, peering at something on the ground. It was a beetle scurrying on the ground.

”Pappa” he said, ”there’s something strange about this beetle!”

We followed it as it meandered amongst through the broken stone and sand. It was beautiful, almost completely white with a few black markings. A white beetle being a novelty, I was keen to get close and take a photograph but the beetle did not cooperate. Realising it was being pursued, the beetle changed tack and now hurried along on a twisting path towards some Aak bushes (Calotropis spp). A picture on the ground was difficult to get so Aashay chased it trying to scoop up the dodging creature. This he did, only to lose it a few seconds later. We did however succeed in taking a few snaps.

What was truly amazing was that the beetle, which was almost completely white when Aashay had spotted it, gradually turned darker and darker until finally it was almost completely black with only a very thin white edging.

The creature finally reached sanctuary – a cluster of Aak roots with twisted branches, dried leaves and small crevices into which it disappeared. The Rajasthani locals who worked the mines told us that the beetle turned black with fright but would recover to its original pattern after 15 minutes or so.

Immediately after we encountered the beetle it began turning black.

Immediately after we encountered the beetle it began turning black.

Scooped up in Aashay's hands for taking a good snap, it has almost turned completely black.

Scooped up in Aashay's hands for taking a good snap, it has almost turned completely black.

Later I put up the images on Wikipedia WikiProject Arthrpods talk page, hoping for an identification. Doug Dynega, an entomologist and museum curator in the States, responded whith what appears to be the key to the mystery:

”It’s a Tenebrionid, but I can’t be certain of the subfamily. From what I can see in the photos, the white “markings” are, like in many desert Tenebs, not markings, but fine cuticular wax deposits. I’d never heard of the beetle being able to change the amount of wax on it, so I have a better explanation, based on what one can observe; the wax layer is hygroscopic (absorbs moisture), and when it does so, it loses its reflectivity. Holding the beetle in your hand will greatly increase the humidity in the airspace near the beetle. This makes some sense as a desert adaptation; when humidity is low, the beetle reflects more sunlight, and when humidity is high, it reflects less. I’ve just never heard of the phenomenon, and can’t confirm it myself. What you need to do is catch one, kill it, and experiment. If it’s that sensitive, even breathing on it should have a noticeable effect. If it can be confirmed, it might even be something to publish, assuming no one has documented it before.”

Sadly, we left the area soon after and could not go back to explore this mystery any further. A pretty little puzzle waiting for someone to unravel it!

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Notes.

1. Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.2 or any later version published by the Free Software Foundation; with no Invariant Sections, with no Front-Cover Texts, and with no Back-Cover Texts. A copy of the license is included in the section entitled “GNU Free Documentation License“.

2.  Comment by Doug Dynega published under GFDL copyright from Wikipedia at the Talk page of WikiProject Arthropods on Wikipediaaccessed on 08 Jan 2009:

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