Species: Pseudagrion microcephalum
Common name(s): Blue Grass Dartlet, Blue Sprite,
Small-headed Sprite, Blue River Damsel
Thai name(s): แมลงปอเข็มบ่อไมโคร, แมลงปอเข็มบ่อฟ้าเล็ก
Habitat: Exposed ponds/lakes, lowlands & uplands
Province(s) sighted: Widespread (Khon Kaen); Nam Nao NP (Petchabun); Chantaburi; farmer's pond (Prachaub Khiri Khan).
Sightings (by me): Very common, especially in Khon Kaen
In flight (that I have seen): October-March (though I suspect all year)
A common, but still stunning species is Pseudagrion microcephalum. I have seen this species on numerous occasions, in many lowland areas. It is easily confused with another species, P. australasiae. Though easy to spot, it is difficult to get good photographs as it seem always ready to fly away at the slightest movement.
The bright blue and markings makes it easy to spot, but it is often confused with P. australasiae. However, it is brighter blue, smaller in size and has longer superior appendages (the black appendages at the end of the abdomen). This is not quite fully adult and I am still trying to get extreme close-ups of the adult male.
The sub-adult male
The young males are seldom seen by the waterside, but if you look in the trees and bushes that surround water where the males are present, it is possible to find them, often close to the females. The colours are very similar to that of the female. He will eventually turn bright azure blue.
The caudal appendages ...
Taking decent photos (or looking in the hand) is the easiest (and most reliable way) to differentiate this species. I will add photos when I get good quality shots - though looking at the male above, you can see how long the appendages are.
Like sub-adult males, the female tends to hide away and only appears in the open when it's ready to copulate.
The female close-up
Often the best way to tell the females apart, is to wait for them to copulate. However, you may be waiting for some time! This copula I saw in Chantaburi.
I have spotted this species many many times in Khon Kaen, as well as many other places. They tend to like ditches, ponds and lakes, but I have seen them from time to time along very slow, almost still streams. I have seen them almost all year round, but they seem most common between October-March.