DRAGONFLIES and DAMSELFLIES – THE ODONATA

by on May.24, 2012, under Fauna, Information, Invertebrates

DRAGONFLIES and DAMSELFLIES – THE ODONATA

 By Amy Prendergast

If you go for a stroll by a lake or wetland on a warm spring day or are fortunate to boast a pond in your own backyard, you are likely to have encountered these delicate insects skimming across the water surfaces, sunlight glinting off their delicate wings. Dragonflies and damselflies belong to two suborders – Epiprocta or Anisoptera (dragonflies)

Zygoptera (damselflies) – of the insect Order Odonata (Odonates). Odonates are easily recognizable by their 2 pairs of long, transparent, wings with lace-like veins, elongate abdomens, and bulging compound eyes that occupy most of the head.

 

Dragonflies and damselflies share similar biological features: both are carnivorous, inhabit areas around water bodies, and lay eggs that hatch into aquatic larvae. They can put on amazing aerial acrobatic displays, speedily manoeuvring and darting about in the air.

Males are very territorial and you’ll often see a male respond aggressively to any other males that dare invade his territory by chasing them away at high speeds.

If you see dragonflies flying in a paired formation, you’re actually observing part of the courtship between a mating male and female. Following a female Odonate’s consent to her suitor, she allows the male to clasp the back of her head (dragonflies) or thorax (damselflies) using a pair of copulatory structures (cerci) on his abdomen. Once attached, the male’s sperm produced in the 9th segment of his abdomen are transferred to the 3rd thoracic segment  – where the male’s sperm sac is located – by curling the tip of his abdomen under itself. Once the sperm are transferred, the female raises her abdomen so the tip connects with the 2nd thoracic segment of the male and she receives his sperm, which can then fertilize her eggs.

Following mating and fertilization of her eggs, the female then lays the eggs in a nearby water source. After hatching the larvae and juvenile stages, known as nymphs, remain in the water. The nymphs have a very different appearance than the adults: they are fully aquatic and bear gills, lack wings, have much shorter abdomens, and a major difference between the adults and nymphs is how nymphs feature a distinct structure on the underside of their heads called a mask. Folded when not in use, the mask is rapidly fired outwards to capture prey with a pair of grasping hooks at the tip. Nymphs have voracious appetites, actively preying upon other aquatic invertebrates and even fish and amphibian larvae. Once the nymphs have completed their juvenile development, they emerge out from the water onto surrounding vegetation, moult their nymphal skin (known as the excuviae), and metamorphose into adults with fully-formed wings.

Whilst having similar biological characteristics, and also appear very similar, there are a few key structural features allowing you to differentiate between dragonflies vs. damselflies:

  • Dragonflies have more robust, larger, broader bodies. The hind wings are broader than the forewings, and when perching, a dragonfly holds its wings out horizontally, perpendicular to the body. Dragonflies tend to dart, rapidly zipping about in flight. Their large eyes meet at the middle of the head.

  • Damselflies have more delicate, slimmer, smaller bodies. Both pairs of wings are of similar size, and they flutter and hover in flight. When perching, the wings are laid-back vertically parallel along the length of the body. Their eyes are separated by a thin segment.


  • Ela Chorak

    Hey thanks Amy – never knew there were the differences in damsel & dragonflies. They are often very captivating to watch skimming across the water.