Although dragonfly larvae have been studied widely, this aspect of their life history still harbours unsolved mysteries. For example, there’s several dragonfly genus whose larvae are still unknown and not found or described. The best way to study larvae ecology is to rear them ex-situ. This requires patience, time and acquired knowledge through practice. Inspired by the excellent work by Dr. Ian Choong from Malaysia and encouragement from Yeh Wen-Chi in Taiwan, I decided to take on this challenge whole heartedly.Two to three days prior to emergence, a typical larva will stop feeding and climb partially out of the water. This is when aquatic respiration slowly change into atmospheric respiration. Once ready it will leave the watery environment into an aerial existence. After rearing this larva for 20 days, a miracle of nature finally unfolded.
Tropical dragonflies mostly emerge at night to pre-dawn. There are four stages of emergence. The first is when the larva search for a suitable support, climbing upwards and away from water. At this stage, the cuticle is still intact.At second stage. the cuticle of the head and thorax split with the adult now pushing itself out of the moult (known as exuvia in dragonflies). Looking at the process, I actually sensed the dragonfly’s physical exertion. Slowly, the head, thorax and legs emerged with only the abdomen still inside the exuvia. Normally, a dragonfly would then rest for a while.
When it has regained energy, it swung forward to hang onto the exuvia and pulled its abdomen out. This is the third stage. The dragonfly is now fully emerged but looks all wriggled and fragile.
Finally in stage four, bodily fluids are pumped throughout the body to expand the abdomen and wings and also gaining full colour. Just like an ugly duckling, its wings open and transformed into a beautiful reddish female Orthetrum chrysis.
The entire four stages require 1-2 hours. Sacrificing sleep from 4-6am to witness this event is certainly worth it. For a dragonfly, it now enters an aerial lifestyle of hunting, territorial fights and procreating the next generation.Orthetrum chrysis is a common dragonfly. Although mostly encountered at forest margins, we can also find them in well-vegetated park ponds. Of the several red-coloured dragonflies in Singapore, males of O. chrysis can be recognised by its red abdomen and blackish-brown thorax.
Pictures taken at: ex-situ, May 2009 (larva and emergence); Bishan Park pond, September 2008 (adult male).
References:
Corbet, P. S. & S. J. Brooks, 2008. Dragonflies. HarperCollins Publishers, London, UK.
Silsby, J., 2001. Dragonflies of the World, CSIRO Publishing, Victoria, Australia.
Aeshnids are unlike most other dragonflies in that females will insert their eggs into plant tissue. This ovipositing mode is the same as damselflies. Aeshnid females have well-developed ovipositors to cut minute slits into plant tissue for egg insertion. This behaviour is seldom seen so I was very fortunate to witness an Anax guttatus with colleagues recently. The videos show a female ovipositing into the floating plant stem. A. guttatus, when not flying at speed, is quite easy to recognise with its overall greenish colour and blue pattern on the abdomen. Up close, it is a beautiful and impressive dragonfly.
This dragonfly is one of two or three species in Singapore that have adapted to back mangrove habitats. It is an inconspicuous dragonfly where males usually perch for long periods defending their territories. Although widespread throughout Sundaland, it breeds only in salty water of back mangroves. It is therefore highly specialised and rather rare. In Singapore, R. bispina is classified as uncommon and has been recorded from only a handful locations.
Two features are used to distinguish this species from others. Raphismia bispina has two downward pointing spines behind the hind legs at the rear of the synthorax. It also has two bifid process projecting from beneath abdominal segment S2. It’s difficult to see these tiny features unless there’s a close-up photograph.
We were lucky to observe a female while on the way out. She has mottled yellowish patterns on the thorax and yellowish streaks running down her abdomen. Like the male, she perched patiently on a branch and we could see that she’s gleaning for prey. She awarded us with good close-up shots and her vulva scale beneath the abdomen tip was visible. This ‘spout’ like structure is where eggs leave the females during ovipositing. Vulva scale is not found in those dragonflies that oviposit into plant tissues.
I love the slight golden tinge on its carapace and abdomen. A closer look reveals a streak of blue on the femur. This makes the spider even more attractive. Using innovative experiments, local researchers have shown that females of another jumping spider species (Cosmophasis umbratica) would spend a longer time observing ultra-violet (UV+) males than UV- males regardless of which male display more actively. This suggests for that species, male UV influence plays a role in female-mate choice. Perhaps similarly, the iridescent bluish leg femora would help a male Banded Phintella in attracting the opposite sex.
Jewels are from the family Chlorocyphidae which consists of about 140 species worldwide, most of them distributed in Asia, Africa and Australasia. These damselflies, with the exception of the genus Rhinoneura, have their abdomen shorter than their hindwings thus separating them from other damselfly species. Another characteristic feature is the presence of an upturn snout which I feel gives them a rather cartoon-ish appearance. 
