Dragonflies and Damselflies (Order: Odonata)
A male Common Blue Damselfly (Enallagma cyathigerum)
The Order Odonata, or dragonflies and damselflies, contains some of the most beautiful and conspicuous insects in Britain. During the summertime, the swift flight of our larger species and their exquisite colouration are bound to attract our attention. Many stretches of water, such as lakes, rivers, ponds and marshes, will attract some of these large insects which can be seen on the wing during the warm sunny days of summer. As such, they are amongst our most well known invertebrates.
Many of our native species are large, whilst even the smaller more fragile species are still large enough for us to appreciate their beauty without the need for magnification.
Nymphs of most species are reasonably easy to rear in their later stages, and the nymphs are fascinating to observe. The equipment needed for the study of these insects is simple and usually inexpensive.
The number of British species is sufficiently small, totalling just 45, to also be of interest to those who study other larger groups of insect.
The Odonata are amongst the oldest groups of insects known, and are not closely related to any other existing Order. The largest known insect is the fossil dragonfly Meganeura monyi, which had a wingspan of approximately 30cm.
Main characteristics of Dragonflies and Damselflies
- Two pairs of wings of similar size and have a dark mark, or pterostigma, near the tip of each.
- Long and slender abdomens
- Large heads
- Very large compound eyes
- Small, hair-like antennae
A photograph of an adult male Broad-bodied Chaser dragonfly (Libellula depressa)
- The small yellowish eggs are laid directly in to the water or inserted in to water plants, floating debris or mud. The males of many species help by holding on to the females and then pulling them up in to the air again.
- The aquatic nymphs take from one to five years to complete their development, according to species. Like the adults, they are carnivorous, preying upon many forms of aquatic fauna. Prey is caught in large pincer-like extensions of their lower lip, known as the 'mask'.
- When fully grown, the nymph becomes restless, ceases feeding and eventually selects a suitable plant stem and crawls out of the water, settling down well clear of the surface. Eventually, the skin splits along the back and the adult insect struggles out, usually at night or very early morning. Soon the wings begin to expand, once dried, the adult is ready for flight. Full colouration usually does not take place until a few days has elapsed. Adult Odonata can be found from April until November, with the life span of an individual lasting no more than a few weeks.
- Adult Odonata are exclusively entomophagous (they eat insects), catching their prey on the wing, and will seize anything small enough for them to tackle.
- Mating takes place either on the ground or amongst foliage, according to the species. The male seizes the female by the back of the neck or hear with special anal appendages, whilst the female curves her abdomen round so that her pairing apparatus can make contact with his, under his second abdominal segment.
There are 2 sub-orders found in the British Isles:
- The Anisoptera, or dragonflies, are characterised by having the hindwing noticeably broader at the base than the forewing. In addition, the eyes meet on top of the head with the exception of one species and they rest with their wings stretched out flat.
- The Zygoptera, or damselflies, are smaller more fragile insects with similar fore and hindwings, have widely separated eyes, and rest with their wings folded over their abdomens.
Collecting adults is best undertaken with the use of a large net on a long handle. Being very able flyers, this will need skill and agility, or considerable luck. Capture is best affected from above and behind. They are usually pinned and set in the same way as Lepidoptera if a collection of set specimens is needed - excellent identification guides have been published and this means that collection is usually unnecessary.
Nymphs are collected by a specific water or pond net, sweeping through submerged vegetation and debris and then searching through the contents of the net. Unwanted items and debris should be returned to the water, and the nymphs taken home in water tight containers. Another way to obtain nymphs, for a dried collection, is to collect the empty nymphal skins left after the adult has emerged. These can be found by searching suitable bankside vegetation.
Even some eminent scientists can be surprised by the size of some adult dragonflies as this quote from Richard Feynman, physicist and Nobel laureate, shows:
So one day I was on the beach, and I'd just read this book that said dragonflies don't sting. A darning needle (dragonfly) came along, and everybody was screaming and running around, and I just sat there.
"Don't worry!" I said. "Darning needles don't sting!"
The thing landed on my foot. Everybody was yelling and it was a big mess, because this darning needle was sitting on my foot. And there I was, this scientific wonder, saying it wasn't going to sting me. You're sure this is a story that's going to come out that it stings me - but it didn't. The book was right. But I did sweat a bit.
Related links: Dragonflies and Damselflies (Order: Odonata)
- British Dragonfly Society - checklist of UK species
- Damselflies - UK Safari
- Dragonflies - UK Safari
- Dragonfly and damselfly image gallery
- Irish Odonata
- Odonata Central
- What is the difference between Dragonflies and Damselflies?
- Worldwide Dragonfly Association
A to Z of insects
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- Leaf insects
- Praying Mantids
- Stick insects
- Sucking lice
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- True Bugs
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- Two-pronged bristletails
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