Sarawak: Some Dragonflies at Bako

By November 18, 2014, my time in Sarawak was drawing to a close. I still had time for a last few excursions, sometimes with my grandson Ryan and sometimes when Ryan was in school.

Here are a few common dragonflies, from a brief trip to a grassy area near Kampung Bako; nothing unusual, but as I was about to leave Malaysia for some time I was glad to see them again.

The genus Neurothemis can be extremely frustrating.  Neurothemis dragonflies are seemingly everywhere in open country in Sarawak - the ultimate ditch dragonfly, as it were.  Finding them is easy; identifying them, though, is another matter.  Of the three common species, two - Neurothemis fluctuans and Neurothemis ramburii - are both variable very similar in appearance.  Size aside, telling which is which can be something of a guessing game.

I'm not saying this just because I'm an amateur.  According to two experts, Malte Seehausen and Rory Dow, "Members of the genus Neurothemis Brauer, 1867 are difficult to identify to species due to the highly variable wing maculation of males and the polymorphism of females."  So there.

Anyway, I think that the dragonfly in these photos is a male N. ramburii because of the long, rectangular space at the base of the wings (the cubit-anal space). N. fluctuans, is supposed to have two or three veins crossing this space.  However, as Seehausen and Dow note, ramburii is a highly variable species, and I could be wrong.

This male Neurothemis terminata is a lot easier to place, because the hyaline (or clear) area at the tip of the hindwing is cut off squarely rather than tapering back towards the body at its rear edge, as it does in the other two species.

Neurothemis aside, probably the commonest "ditch dragonfly" in Sarawak is Orthetrum sabina, a very wide-ranging insect indeed, ranging from southeastern Europe and North Africa to Australia, Micronesia and Japan.

Another puzzler (at least to me) is Orthetrum glaucum.  This, too, is a variable species, with the males differing in the extent and intensity of blue on the abdomen depending on the reach of the powdery covering, or pruinosity, covering it (if the pruinosity is rubbed off what is left is simply a black exoskeleton).

Some males, like this one, can be very light indeed, with strongly blue eyes.  In West Malaysia I would have put this down as a related species, Orthetrum luzonicum, but luzonicum is not supposed to occur in Borneo, so glaucum it must be.

Orthetrums come in a variety of designer colours, including red.  This one, with an extensively red-orange thorax, is presumably Orthetrum testaceum.

Finally, just to show that I can look at an insect that isn't a dragonfly, here is a handsome wasp: the Lesser banded hornet (Vespa affinis).  This is not an animal to be taken lightly; its sting has caused human fatalities.