The life-cycle (and life-style) of most dragon and damsel flies

The first thing to know is that all the odonata are vicious, thoughtless predators, and have few redeeming features. From the moment they hatch out of their eggs, they are fighting - for safety, for food, for mates and for territory. They are voracious carnivores, and eat a lot of smaller insects, sometimes landing to eat and sometimes eating in flight. Flying is hard work, requiring quite a lot of energy, and these animals are pretty small, without a lot of reserves, so they have to eat frequently just to keep participating in the mating games. As well, in some cases, as behaving like bullies: I have seen a sentry dragonfly who was clearly not a happy beast barge into a linked pair of common redcoat damsels, just because he could; the male victim was stunned, and floated upside down on the water for about half a minute before he could fly again.

But ... within their limitations dragonflies are intelligent, and can be curious and inquisitive. Some of the photos in the site show that the animal was staring at me - and I had once decided that a particular swamp contained no dragonflies when one flew up, looked me up and down (I could see its head move), almost audibly sniffed in disdain, and flew away. They are also physically attractive (to a photographer), as well as a challenge to photograph well. And as, in most cases, they are not urban animals, photographing them can require some exercise, during fine weather, and sitting quietly beside water, to get to where they live. A bit like fishing, except you can avoid wet and windy days - the animals do!

One thing that dragonflies do that damsels don't is to hover. I have spent many hours photographing empty swamps to get these photos. It seems pretty clear that they hover by flying forwards with the front pair of wings, and backwards with the back pair; when you think about it, anything else would mean they were clashing their (fragile) wings, and would very soon damage themselves beyond viability. Note that wings don't heal - have a look at the damage on the wings (half of each left wing is missing, the trailing edges of both the right wings are ragged) of the beast standing on my hand on this page of the site!

Please note the word "most" in the headings. Two dragonflies, the bush giant and the mountain giant, don't oviposit in ponds, lakes or streams. All the damsels and the rest of the dragons do. For the immediate discussion, I shall discuss only the ones that oviposit in water. To skip to the discussion of the giants, click here.

Mating in the odonata is a complicated process. First the males have to attract the females, and guard the area where he wants them to lay his eggs. He flies about in his chosen area, driving away rival males, and at the same time trying to show off his flying (as well as his fighting) skill for the females watching from the vegetation nearby. After a while a female may approach - or at the very least, make herself available - and the game moves into another phase. The male will grasp the female by the front of her thorax with his tail, and they will remain joined thus for some time. At this point, the female is in control of what happens, as she has to join her sexual parts with his - the end of her tail to the back of his thorax, behind his legs - and if she doesn't, there is nothing he can do to make it happen. If she is receptive, then they mate, but he still doesn't let her go. As a part of the process, he has cleared out any sperm she already had within her, so that when her eggs are fertilised and laid they will be his offspring and noone else's, and the only way he can ensure that is to hang on to her until she lays the eggs. Fertilisation is not instantaneous, so there is a bit of waiting; they stay linked until she is finished laying. Meanwhile, rival males are trying to disrupt the process and separate the pair to try their best to produce another generation of their own. It certainly helps to keep the genes strong!

There is a range of laying approaches used by different species, depending on what is available to them. The common redcoat female first cuts a small slot in the stem of a plant which protrudes through the surface, near the water level, and then she deposits one or more eggs in the slot (as in the picture on the left). Other animals are less careful, in some cases merely "dive bombing" their eggs onto floating pond weed, where they can hatch and start to fend for themselves, or into the water in the expectation that the eggs will sink into the detritus on the bottom before they are eaten by fish or by other invertebrates. Whatever method they use, that is the end of her interest in the process.

The eggs hatch after a few days into a "nymph", initially small but it grows; an insect with a mouth and lots of attitude. They resemble the cicada nymph in a lot of ways, except that they are entirely aquatic, and they spend their time trying to prey on other small animals while remaining uneaten themselves. Cannibalism is far from rare. As they get larger, they become more of a threat to the other denizens of their environment; there are records from overseas of dragonfly nymphs attacking tadpoles and small fish. Because, like all insects, they have their skeleton on the outside, they go thorough a number of skin changes in the year or several before they are ready to hatch into adults.

When the nymph is ready to hatch, it climbs up a plant stem to a few centimetres above the water, and hangs there while the process of getting out of the aquatic body takes place. This is slow, and some species, in some places, lose a lot of representatives to trout, to birds and even to feral cats during this period. Ideally it takes place in darkness, and within vegetation, but that is not always possible. And once it has extracted itself from the nymph case, the adult animal has to (literally) spread its wings and unfold its body. The final stage of the nymph of the sentry dragonfly, for example, is about half the length of the adult animal - and of course, it doesn't have its wings until the hatching is over. And at the same time as all this overt activity takes place, the animal is also changing from breathing through gills to breathing air. A lot is happening! The adult does not change its exoskeleton, so once it reaches as big as it can make itself now, that is the size it will be. As soon as it can, the adult flies (probably not very well!) away from the water - and rivals of its own kind, as well as threats from predators - to finish its transformation.

Some adult odonata move a long way from their emergence site - kilometres - and some only a few metres, but they all go to places where they are safe, able to recover from the hard work of transformation, learn to fly, and eat to gain the muscle and energy reserves to start the whole cycle again. And then they go back to the battlefield, and it all starts again.

Once the animal is a flyer, it lives only until the end of the summer. And in the meantime it remains vulnerable to wind (bashing it against vegetation) and rain (they are neither very big nor very strong).

The Giants

These beasts - the bush giant, really, as I haven't looked for dragonflies outside the North Island so far - are my favourites. To start with, they are not only endemic to NZ, they are of a rare (and "phylogenetically primitive") type which doesn't lay their eggs in water. Instead, they lay their eggs in permanently wet ground. I have seen a female bush giant laying her eggs in soil round a tiny waterfall from a spring at the top of the Wellington Northern Walkway, and I know of a burrow site in the Wainuiomata water reserve. The female is solo when she is laying, and Rowe suggests that they may lay in the places where they themselves emerged. Certainly the one I saw laying later passed me, flying at least a couple of kilometres on her way to the nearest bush in that direction (having turned her back on the bush surrounding her laying site).

When the eggs hatch, the larvae then tunnel deeper into the soil, until they are both secure and partly below the water table, when they spend their days with their gills (tail) in the water. At night apparently they fill their abdomens with water - a different kind of aqualung! - and stalk small insects on the soil above the burrows. And, also from the book, they may be in the larval form for some years. Then they hatch, and live to the end of the summer.

I think the reason I feel fond of them is that in a couple of the cases where I have seen them, they have been content to be offered a finger to stand on. They do seem to like being told how pretty they are, and to pose for a camera. The one whose photo on my hand features on the site was posing (on twigs as well as the hand) for about 10 minutes before I thought I had enough pictures, and walked on. Naturally, I thanked him for his time. In Wellington, I only encountered them when they were alone: at the top of the Rimutaka Incline track, the top of Tinakori Hill, by the Brooklyn wind turbine, on the Makara Opau loop track and in the bush on Reservoir Road in Wainuiomata. Since my move to Auckland, I have seen far more of them, flying about at the edge of bush near my home, usually in twos or threes. I can only assume that this was mating behaviour, as there was no clear aggression taking place.

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