 |
|
An Introduction to Dragonflies and Damselflies
Dragonflies and damselflies are the raptors of the insect world. Voracious hunters as larvae in ponds, rivers and lakes, they sometimes take prey as large as sticklebacks. They continue in the same vein after they have emerged as flying adults, hunting smaller insects on the wing in dashing raids. The larger dragonflies will take prey as big as the damselflies, but they are all absolutely harmless to us - they do not sting or bite in any way, and are actually very easy to handle, perching readily on a finger if trapped in a window. Their fascinating looks, amazing habits, and relatively tame manner combine to make the most exciting close-up wildlife watching experience in Britain.
Unlike many insects (such as butterflies, moths, beetles and flies) dragonflies and damselflies (together with mayflies and grasshoppers) have a three-stage life cycle. They are 'hemimetabolous', having and incomplete metamorphosis. The missing stage is the pupa - hemimetabolous insects go straight from larvae to adults. The insects which do have a pupal stage are known as 'holometabolous'. Adult female dragonflies lay eggs either on submerged vegetation or directly into water, and generally they will hatch after 2-5 weeks. Some eggs laid in late summer will go into diapause during the cold winter months and hatch in the spring. Most then remain as larvae for one or two years, preying on a range of tiny underwater creatures, although some of the larger dragonflies can take three years. The Golden-ringed Dragonfly, not recorded in the county but resident in the Midlands), can be in the larval stage for up to five years.
There are over 5000 species of odonata worldwide, and being warm weather insects, it is not surprising that the majority are found in the tropics. At least 55 species have been recorded in the UK, of which around 40 are resident. In Leicestershire and Rutland there are 20 resident species, and the full list totals 26, which includes three rare immigrant species from Europe - Lesser Emperor, Yellow-winged Darter and Red-veined Darter. Identifying dragonflies can in some cases be very difficult, even for the experts. But many, especially the mature males, have vivid colours and distinctive patterns, so everyone should be able to identify at least some of them. The first step is to understand the difference between dragonflies and damselflies. Dragonflies (like this Four-spotted Chaser, below left) are generally big with a thick, either tubular of slightly flattened 'tail' (abdomen) and broad wings, broadest where they meet the 'body' (thorax). They have huge compound eyes which take up much of their face. The eyes join in the middle on top of the head. A good look at the face will reveal a gruesome set of jaws!
Damselflies (such as the Azure Damselfly, above right) are smaller, and are dainty, elegant insects. They have a long, thin, tubular abdomen, narrow wings, narrowest where they meet the thorax, and large eyes (although much smaller than dragonflies) which protrude from the sides of the head, almost as if on stalks. One further difference is the way they hold their wings. Dragonflies almost always have their wings spread fully open, and can be found perching on vegetation, often hanging vertically. Damselflies habitually close their wings when at rest and hold them over their 'backs'. One damselfly, the Emerald Damselfly, usually holds its wings open at 45 degrees. Dragonflies and damselflies can be told from other winged insects is several ways: they are large, with long, stout (or very wide) abdomens, large eyes, very short antennae, and many are brightly coloured blue, red, orange, brown, yellow and green. Dragonfly and Damselfly Anatomy
GlossaryIn addition to the anatomical terms mentioned above, several other definitions are used on this website, and in general to describe odonata. Here are a few:
For more information...All the Leicestershire & Rutland species are included in our species accounts: just look through the links in the left column. Each species account includes notes on identification, status and habitat, a map of occurrence in the county, and flight period graphs depicting the exact season you should see each species on the wing. There are lots of excellent local and national odonata websites - see the links page. Most of the information on this page, and much more, is contained in an excellent book by Steve Brooks: Field Guide to the Dragonflies & Damselflies of Great Britain & Ireland. To ask a question, please contact us. |
Welcome to the wonderful world of insects! Dragonflies are an integral part of summer, flitting over ponds and skimming across rivers on balmy afternoons. But behind the beautiful colours and graceful flight lies an exciting and dramatic creature indeed!
Dragonflies and damselflies are in the insect order 'odonata', which translates as 'toothed jaws'. They belong to the most primitive group of insects; incredibly, some of their predecessors 300 million years ago reached a wingspan of up to 70cm, and could fly at 30mph! Odonata worldwide are divided into three sub-orders: Dragonflies (Anisoptera), Damselflies (Zygoptera) and a very primitive sub-order (Anisozygoptera) that is now almost extinct.
When they are ready, the larvae climb out of the water on a reed stem or piece of vegetation, and then emerge from their larval case (or exuvia) as adults, which is what the Blue-tailed Damselfly is doing (above right). Careful searching in vegetation emerging from ponds, canals, lakes and rivers can often reveal an exuvia like that of the Four-spotted Chaser (right). Just after emmergence, they are very vulnerable to predators until they have pumped their wings full of fluid and have then dried out, ready for flight. The flying adults have a short life-span - some can live for six or seven months in hot, dry climates, but typically in the UK the insects fly for just a few weeks.
|