Dragonflies are a group of insects scientists call the Odonata. Like all insects they have a hard exoskeleton, made of chitin (pronounced: kite-in) and proteins. They have six segmented legs and their bodies are divided into three main parts: head, thorax and abdomen.

The freely movable head has two large compound eyes and three simple eyes, called ocelli. The antennae are small, while the jaws are large with several sharp teeth. “Odonata” is Greek for “toothed ones”.

Watch a dragonfly's jaws in action.
(Video = 0:25, 0.8 Mb.)

Classification of Dragonflies










Anisoptera (true dragonflies)


Zygoptera (damselflies)


Watch a higher resolution version of this video on YouTube. Click Here: Jaws in Action!


Dragonflies have two pairs of clear wings and three pairs of legs attached to the thorax. The wings are strengthened with net-like veins which have a unique pattern for each species. The thorax is slanted upwards. This brings the legs forward for perching on upright stalks and to form a basket for catching flying insects. Long spines on the legs help catch prey in flight. Dragonflies rarely use their legs for walking. The thorax, with the powerful wing muscles, can be 60% of a dragonfly's weight.

The abdomen is long, thin and very flexible. It has 10 distinct segments. Males have appendages on the end of the abdomen, called claspers, to hold onto a female during mating. The reproductive organs are located in the abdomen.

All insects breathe through tubes called trachea that allow air to pass directly to their inner tissues, bringing oxygen in and taking carbon-dioxide out. The trachea open to the outside air at holes along the thorax and abdomen called spiracles.

Food passes from the mouth to the foregut where it is ground up, then on to the midgut for chemical breakdown and nutrient absorption. In the hindgut water and minerals are absorbed and feces are passed out through the anus.

Insects have an open circulatory system with a simple heart, a section of vessel in the abdomen that pumps hemolymph (insect blood) to the front of the body. It returns to the abdomen through open sinuses.

The central nervous system is simple with a dorsal brain and ventral nerve cord containing enlargements called ganglia. Each ganglion is like a mini brain controlling nerves within its region of the body.

There are two groups within the Odonata: the true dragonflies (Suborder: Anisoptera) and the damselflies (Suborder: Zygoptera). Here’s how to tell them apart:

1. Head and Eyes: In true dragonflies the head is rounded and the compound eyes touch each other at the top (except in one family). In damselflies, the head is wide, almost dumbbell-shaped. The space between the compound eyes is wider than the eye itself.

2. Wings: Anisoptera means "unequal wings". In true dragonflies the second pair of wings is broader than the first. A dragonfly at rest spreads its wings apart, like a moth. Zygoptera means "equal wings". Both pairs of a damselfly's wings are similar. At rest, most damselflies hold their wings together, above the body, like a butterfly.

3. Shape and Flight: Dragonflies are usually larger and stouter than damselflies and they fly strongly, out in the open. Damselflies have very slender bodies and are weaker flyers, usually fluttering near the ground or by thick vegetation.

For convenience, the word “dragonfly” is used here to refer to both dragonflies and damselflies most of the time.

1) Basic Biology

2) Life Cycle

3) Palaeobiology

4) Biodiversity

5) Biogeography

6) Overwintering / Migration

7) Food

8) Sight and Flight

9) Cultural Significance

10) Conservation

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