ON AN OUTING one sunny afternoon in November 1992, I came across a tiny, peculiar-looking insect.
I got a shot of it with my camera. Just as I had it in focus again, it flew away and denied me a second shot.
I did not know what it was, and I had seen it only briefly. When I
got my colour slides back from the processing lab, I quickly looked for that single shot.
Could it be a stalk-eyed fly, a creature that I had read about but had never seen before
this?
I consulted an executive officer at MNS (Malaysian Nature Society) headquarters and she had no doubt
that it was a stalk-eyed fly when I showed her the slide. Name of the species? On her
suggestion, a duplicate of the slide was sent to Germany. Megalabops quadriguttata,
came the reply from Dietrich Burkhardt and Ingrid de la Motte, a couple of experts who
have been studying and collecting these insects from all over the world.
How about an article for the Naturalist? she asked. One picture and
a name were not much to go on. So I went back to the spot, a popular forest recreation park
with waterfalls and a stream running through it, to stalk the stalk-eyed fly. No luck.
I went back again and again, widening the area of search each time. Still nothing.
Some months later, I think it was April 1993, after having given up the
search, I stumbled upon a stalk-eyed fly at another spot, some distance from the first
location. It was flying among leaf litter and rubbish thrown by picnickers under some trees
beside a waterfall. Not quite prepared for this encounter, I managed to get only a couple
of pictures, not very good, but close enough to show that this species looked different
from the first one.
I returned to this second site in November 1993 and was fortunate to
find several specimens. This time, equipped with the right optics, I got a number of pictures,
including some "eyeball to eyeball" shots, i.e. close-up frontal shots.
I should have known that I need not have to go far for identification.
On making inquiries at FRIM, Kepong, I was directed to Dr Yong Hoi Sen at the University
of Malaya. I was told he keeps a collection of preserved specimens at his faculty.
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Without hesitation he identified the species I have captured on film as Cyrtodiopsis dalmanni,
the most common of the twelve* Malaysian species.
As you can see (from these photos), stalk-eyed flies are unique among insects in having eyes
borne at the end of rather long, lateral stalks.
The vision of these creatures is the subject
of research by Burkhardt and de la Motte. They have been coming to Malaysia every year to
collect the various species, I was told. They also culture these insects for their study. The
couple has written a paper "The puzzle of the stalk-eyed flies..." for The MNJ** (Vol 39, No 3).
Stalk-eyed flies belong to the insect family Diopsidae. While only twelve*
species have been recorded for Malaysia so far, Africa has a far larger number of species. Some
of the African species are pests of rice, maize and sorghum, causing extensive damage to these
crops. The Malaysian stalk-eyed flies, I have been told, are quite harmless although certain
species are also to be found in rice fields.
(This article was published in the Malayan Naturalist, Vol 48 Nos 2 & 3, Aug/Nov 1994.)
* New species of diopsids have been discovered since this article
was written. I believe the number recorded for Malaysia so
far is close to twenty.
** The Malaysian Nature Journal.
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