Since the last blog that I wrote about The Dragonfly Project, I have noticed the increasing hues of red and blue Dragonflies circling around me. They are all returning and it has made me more and more excited to start the Dragonfly count in the Sand River. I was on a drive recently and I had a dragonfly fly into my face and hit me right on the cheek. This is unusual due to their keen eyesight and incredible manoeuvrability.
A few weeks later, also while on a game dive, I had another dragonfly fly alongside me in the driver’s seat as we drove around for a while. It might have been a hint to get myself back into action and start the Dragonfly Project soon! I have started to read up on Dragonflies to get as much information as I can to be ready to do the count in the peak of summer when dragonfly populations should be at their highest and they are the most energetic.
Dragonflies have been on my mind a lot.
Dragonflies are diurnal, mostly active during the middle part of the day. They will often tuck themselves away in bad weather, cold or windy times to conserve energy. Their four large independent wings which give rise to their extreme manoeuvrability and hefty appetite make them voracious predators that not many other insects can escape.
Vision is their primary sense and is probably unmatched by any other insects or animals out there, with two large compound eyes, each hosting thousands of lenses, and three eyes with simple lenses. Which compensates for their small or underdeveloped antennae that limit or inhibit the ability to hear and smell.
Dragonflies, are the ultimate insect predator and occupy an equivalent niche to the large preators of Londolozi, such as lions and leopards, as well as the eagles of the bird world.
A male leopard chasing a herd of impala, as you can see here he has locked on his target while an explosion of animals happens around him, just like a dragonfly that can catch its prey while in flight and lock onto one insect in a whole swarm.
The Life Cycle of a Dragonfly
Although we tend to always notice dragonflies near water, they are only dependent on the water during their reproductive stages where they need to lay their eggs in the water. Hence the ones you see will be the breeding adults and they are likely to stay near the water in order to find a mate. Mostly, males will spend time defending their breeding sites from other competing males. Although, females may only visit waterholes when they are ready to lay their eggs. You can quite likely find non-reproductive dragonflies far from the water.
The lifecycle of a dragonfly is centred around water. The eggs are laid in the water, and the nymph hatches and lives within the water until it emerges and metamorphosises into an adult, who then returns to lay eggs within the water.
Courtship is limited in dragonflies, a male will scan the waterhole for an appropriate female. Once he locks eyes on a suitable one he approaches from behind, grabs hold of her thorax with his legs and sometimes may bite her in an effort to subdue her. He pulls his abdomen forward and clasps the female by the neck with his anal appendages (cerci) while continuing to fly with her in a formation known as a tandem linkage.
The tandem linkage in flight.
He then prepares for copulation by transferring the sperm to his penis. The next part is tricky because the penis is where you would expect it to be, at the end of his abdominal segment, but the female’s genital opening is located near her neck. Once the sex organs are linked, the dragonfly couple forms a closed circle with their bodies, sometimes in the shape of a heart, which sounds very appropriate but is not necessarily the case.
Female dragonflies may mate with multiple males, and only the last sexual partner will be the one to fertilise the eggs, the male dragonfly will attempt to scoop out the sperm of the previous male with barbs on his penis. Once he has cleaned it out he will position his sperm with the best fertilisation potential. He then stands guard to ward off any other males hoping to mate with her. All this happens within seconds.
A pair of Red Groundlings perched above a waterhole. The male is on the right with its vivid red colour and the female demonstrates her buff colouration.
The period between the laying and hatching of the eggs is dependent on the temperature of the water, ie. if the water is warm the eggs develop faster and the period is shorter. If the water is cold the period is longer. So if the eggs are laid late they may not hatch before the following summer.
Once the nymphs have hatched, they will remain in this stage for a year or more for the larger species. During this nymphal/larval phase, they need to shed their exoskeleton in order to grow. The exoskeleton is a rigid layer that cannot stretch. Shedding allows them to grow into their new larger exoskeleton. Eventually, after a few of these stages, the nymph crawls out of the water, sheds its last nymph exoskeleton and transforms into an adult. This can take 20 minutes for smaller species or up to an hour or more for larger species.
A section in The Sand River that would be suitable for many Dragonfly species to lay their eggs in.
After this, the adult lifespan is hard to say but it ranges from a few days (up to 40-80 days). With a little more insight into dragonflies and their lifecycles, I hope we are slowly helping you become more invested in dragonflies and look forward to getting the ball rolling with the project.
Jess Shillaw
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