Tuesday, June 16, 2009

Odonata ( dragonflies & damselflies)

The images taken in this post are all from the same sunny day in December 2008 at Mount Anan Botanical Gardens, near Sydney around a small dam.

I always look for dragonflies and damselflies when I'm near any fresh water. I love the different colours that they come in. Often it is not obvious how beautiful they really are until I see the photos on the computer. On a sunny day with lots of different species flying around I feel like a kid in a lolly shop and never know which one to try and photograph first.

This is a Blue Skimmer or Orthetrum caledonicum, a member of the Libellulidae family and is found right across Australia. This is the male: the female is yellow and black.

Not a lot of vegetation surrounds the edge of the dam but there were a number of sticks towards the middle that the dragonflies used to perch on. There are two different species sitting on the stick above. These two are both members of the Libellulidae family. The top one is a Graphic Flutterer or Rhyothemis graphirtera. The lower one is another Blue Skimmer.

There were a few of these red dragonflies which are called Scarlet Perchers or Diplacodes haematodes, another member of the Libellulidae. This one is flying, patrolling the edge of the dam.

Damselflies can be distinguished from the dragonflies not only by their finer body shape but also the way they hold their wings when they rest. Damselflies generally hold their wings together along the length of their body whereas dragon flies wings sit at 90deg to its body like the red one above. (there are a few exceptions where damselflies do hold their wings like a dragonfly)

This is a Red and Blue Damsel or a Xanthagrion erythroneurum. It is a male indicated by the fact that it has bright blue markings at the tip of the abdomen which females do not. These pretty little damsels are found nearly all over Australia, (with exception of Cape York) and also New Zealand, Fiji and New Caledonia. If you look at the wing tips you can little dark patches. All dragonflies and damsels have this (and some other insects as well). It is called a pterostigma, (which literally means wing mark) It has been recently realised that this little bit of colouring is actually an area of the wing that is a bit thicker and stiffer than the rest of it. It keeps the wings from deforming when the insect is flying...must help out with accuracy and sharp turns no end. Because they have such amazing flying abilities, research is being carried out on dragonflies so that we can build technology with the same abilities. (of course you guessed it...for military purposes.) 350 million years of evolution has refined the design of the wings and strengthening veins so well that it makes Leonardo's flying machine models look extremely simplistic.

This female damsel is laying eggs under the vegetation. There can be quite distinct colour differences between male and female damselflies and dragonflies. Even males that are very colourful when they are fully mature may be quite dull and almost like a female in colour when they first emerge out of the water.

The little blue spots on top of the eyes called postocular spots and are only found on some species. They are one on the characteristics that help identify an individual.

After mating the male damselfly often holds onto the female until she has laid her eggs to ensure that she doesn't go off with another male.

Both these photos were taken at Mount Anan, near Sydney NSW. This pair of damselflies are in the process of laying eggs. The male (the blue one) holds the female as she deposits her eggs on the underside of a leaf.

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