The order Odonata is divided into three suborders: The Zygoptera, or damselflies, which can fold their wings over their abdomen, the Anisoptera or Dragonflies which can't, and thus hold their wings straight out from their thorax, and the Anisozygoptera, an ancient suborder possible once containing the seeds of both the other 2 more modern suborders but now containing only two species from Japan.
You are likely to see plenty of dragonflies as you go out into the field in late summer, normally near water. They are more common in warmer parts of the world. In this order, the dragonflies have strong biting mouthparts and are active and aggressive carnivores, both as adults and as young, which are called nymph. They prey mostly on other insects. The adults have really large eyes, which may contain up to thirty thousand individual lenses or ommatidia. Because of these large amounts of lenses, dragonflies have exceptionally great eyesight and have been known to respond to stimuli up to forty feet away. Though they may have great eyesight, they have poorly developed antennae.
They have two pairs of almost equally sized long, thin membranous wings. Both pairs of wings usually have a stigma, a dark or colored patch near the middle of the leading edge, and a mass of cross veins giving them the appearance of a mesh-like material. Unlike most insects, which either flap both pairs of wings in unison, for example bees and butterflies, or only flap the hind pair, beetles, or only have one pair, flies, dragonflies can flap or beat their wings independently. This means the front wings can be going down while the back ones are coming up. You can see this happening if you watch closely. Dragonflies are excellent flyers, and can even fly backwards.
Dragonflies are a very ancient order of insects. Fossils exist from more than 300 million years ago. Dragonflies are also relatively large insects, even now, but in they past they were much larger. Fossil remains of some...
Cited: Earth-Life Web Productions. 24 February 2000. http://www.insectworld.com/main/odonata.html
Please join StudyMode to read the full document