ODONATA: DRAGONFLIES AND DAMSELFLIES
Definition
- Adults have two pairs of wings, often with lots of cross-veins which give a netting-like appearance. The antennae are small thread-like but the eyes are large for good vision.
- The larvae have a mask, a unique type of extendable, hinged mouthparts so that the jaws can zap forwards to grab prey. Adults have more conventional jaws for biting and chewing their prey.
- The life history lacks a pupal stage:- thus egg, larva which resembles a small adult without wings, and adult. The larvae are aquatic.
- There are 2 major types:-
- Damselflies. Both pairs of wings are very similar in shape. The larva has three leaf-like gills at the hind end of the body.
- true Dragonflies. The hind wings are broader than the front pair. The larva has it's gills out of sight inside the end of its abdomen.
- In size they range from a wing-span of 50 mm to 60mm.
What they do & where they live
- All are predatory as adults and larvae. Adults mainly feed on flying insects. Larvae are aquatic and eat other invertebrates and even tadpoles and small fish.
- Distribution is limited by the availability of suitable aquatic breeding sites. Ponds, ditches, canals, streams, rivers, gravel pits and bogs are the main places chosen by various species, providing they are in a reasonably natural state and without significant pollution.
Number of species
- The British fauna has about 50 resident breeding species, plus about 10 others that are found fairly often as migrants.
- The world fauna is roughly 5,500 described species.
It's amazing 300 million years ago there were dragonflies with a wing-span of half a metre or more, in swamps that became coal in Britain.
