Anisoptera - Dragonflies
Dragonflies are insects in the sub-order Anisoptera (meaning "unequal-winged"). Hind wings are usually shorter and broader than forewings. They are usually large, strongly flying insects that can often be found flying well away from water. When at rest, they hold their wings out from the body, often at right angles to it. The eyes are very large and usually touch, at least at a point. The larvae have no external lamellae (gill plates).
The labelled diagram below may help to define the various anatomical terms used in the descriptions in the species pages.

In Great Britain and Ireland there are about 30 species that may be encountered and one that has become extinct. These species fall into 5 families and 14 genera. A partial taxonomic "tree" for the dragonflies is shown below.
- Family Aeshnidae
- Aeshna caerulea - Azure Hawker
- A. juncea - Common Hawker
- A. mixta - Migrant Hawker
- A. affinis - Southern Migrant Hawker (migrant/vagrant)
- A. cyanea - Southern Hawker
- A. grandis - Brown Hawker
- A. isoceles - Norfolk Hawker
- Anax imperator - Emperor Dragonfly
- A. parthenope - Lesser Emperor
- A. junius - Green Darner (vagrant from USA)
- A. (Hemianax) ephippiger - Vagrant Emperor (migrant/vagrant)
- Brachytron pratense - Hairy Dragonfly
- Family Gomphidae
- Gomphus vulgatissimus - Common Club-tail
- Family Cordulegastridae
- Cordulegaster boltonii - Golden-ringed Dragonfly
- Family Corduliidae
- Cordulia aenea - Downy Emerald
- Somatochlora metallica - Brilliant Emerald
- S. arctica - Northern Emerald
- Oxygastra curtisii - Orange-spotted Emerald (extinct in GB & Ireland)
- Family Libellulidae
- Libellula quadrimaculata - Four-spotted Chaser
- L. fulva - Scarce Chaser
- L. depressa - Broad-bodied Chaser
- Orthetrum cancellatum - Black-tailed Skimmer
- O. coerulescens - Keeled Skimmer
- Crocothemis erythraea - Scarlet Darter (migrant/vagrant)
- Sympetrum striolatum - Common Darter
- S. nigrescens - Highland Darter
- S. vulgatum - Vagrant Darter (migrant/vagrant)
- S. fonscolombii - Red-veined Darter (migrant/vagrant)
- S. flaveolum - Yellow-winged Darter (migrant/vagrant)
- S. sanguineum - Ruddy Darter
- S. danae - Black Darter
- S. pedemontanum - Banded Darter (migrant/vagrant)
- Leucorrhinia dubia - White-faced Darter
- Pantala flavescens - Wandering Glider (migrant/vagrant)
