There are several questions about Dragonflies and Damselflies that are often asked. This page attempts to answer some of those questions. We can't promise that you will find the answer to the question that is of most interest to you here but if you have a question that you think we may be able to answer please send us your question and we will do our best.
- What is the difference between Dragonflies and Damselflies?
- Do Dragonflies Bite or Sting?
- Why are they called Dragonflies?
- How long do Dragonflies live? Is it true that they only live for one day?
- What's the biggest/smallest dragonfly?
- How fast do they fly?
- How quickly do Dragonflies get their adult colour?
- What is the lifecycle of the Dragonfly?
- What do Dragonflies eat?
- Can I use Dragonflies to control mosquitos or other flying pests?
- What enemies do Dragonflies have?
- Are there any legends and myths about Dragonflies?
- Do Dragonflies have antennae (feelers)?
- Why do Dragonflies sometimes appear in large swarms?
Dragonflies and damselflies belong to the insect order known as Odonata, meaning "toothed jaw" - their mouthparts are serrated. They are often referred to collectively as "dragonflies", however there are two different sub-orders.
Damselflies are insect in the sub-order Zygoptera (meaning "yoke-winged"). All four wings are near enough equal in size and shape. They are usually small, weakly flying insects that stay close to the water margins or water surface. When at rest, most species hold their wings along the length of their abdomen. The eyes are always separated, never touching. The larvae have external plates (lamellae) at the end of the abdomen, which act as accessory gills.
Dragonflies are insects in the sub-order Anisoptera (meaning"unequal-winged"). Hind wings are usually shorter and broader than Fore wings. They are usually larger, 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.
No, although large dragonflies if held in the hand will sometimes try to bite, but fail to break the skin. They have a lot of "folk names" which imply that they do (such as Horse stinger), but they don't use their egg-laying tube (ovipositor) for stinging. They also don't bite (people) but they are a fearsome predator of other flying insects.
Possibly the earliest reference to the name is from Francis Bacon's "Sylva Sylvarum: or a Naturall Historie in Ten Centuries." (a curious hotch-potch of experiments, observations, speculations, ancient teachings, and analytical discussions on topics ranging from the causes of hiccups to explanations for the shortage of rain in Egypt). It was artificially divided into ten chapters, each consisting of one hundred items and was published in 1626, where he first used common name "Dragon-fly". At a guess, Bacon had picked up on a common, folklore name in use at the time. Prior to this date (and since) many different vernacular names have been used. Some are: Adder Bolt, Snake Doctor, Devil's Riding Horse, Horse Stinger and Devil's Darning Needle.
There is an excellent paperback called "Spinning Jenny and Devil's Darning Needle" by M. Jill Lucas which has a great deal about dragonfly folklore.
At the shortest, a dragonfly's life-cycle from egg to death of adult is about 6 months. Some of the larger dragonflies take 6 or 7 years! Most of this time is spent in the larval form, beneath the water surface, catching other invertebrates. The small damselflies live for a couple of weeks as free-flying adults. The larger dragonflies can live for 4 months in their flying stage. In Britain, lucky Damsels seldom go more than two weeks and Dragons more than two months. Most Damsels rarely go more than a week, and Dragons two or three weeks. They die from accidents and predation, and large numbers from starvation - in poor weather neither they nor their prey can fly.
No insect has a lifespan of only one day - even mayflies (not closely related to dragonflies) live for several months underwater as larvae before emerging as winged adults. Adult mayflies may only live for a day or so as they are dedicated "breeding machines". They cannot feed as adults as (most) don't have any functional mouthparts.
In the UK dragonflies reach a length of about 85 mm and a wingspan of about 120 mm. This is the size for the larger "Hawker" dragonflies such as the Emperor and Brown Hawker. Damselflies, which are the much smaller and weaker flying relatives of dragonflies, are much smaller. The largest in the UK are the Demoiselles. These have a body length of about 50 mm and a wingspan of about 60 mm.
The biggest wingspan of a living dragonfly is the Central American Megaloprepus coerulatus with a wingspan about 19 cm. This is a thin, long-abdomened damselfly. The bulkiest dragonfly may be Petalura ingentissima from Australia (female wingspan to about 16 cm), a central African Anax species or a reported, but apparently uncollected, aeshnid from Borneo. Perhaps the smallest Dragonfly is Nannophya pygmaea from east Asia including Malaysia and Japan. This species is only 15 mm long with a wing span of about 20 mm.
In prehistoric times dragonflies were much larger, the largest flying insects ever. The largest member of the extinct Protodonata was the Permian Meganeuropsis permiana with a reconstructed wingspan (based on fragments, scaled to complete fossils of similar animals) of about 70-75 cm.
All the links in this answer take you to photos, displayed in a new browser window, outside the BDS web site.
The maximum speed of large species like the hawkers is around 10-15 metres/sec, or roughly 25-30 mph. Average cruising speed is probably about 10 mph. Small species, and especially damselflies, are generally slower, although many medium-sized species can probably keep up with the largest ones.
When dragonflies and damselflies first emerge from their water-borne larval stage, most have very muted colours. Depending on weather conditions, it can take a few days for them to gain their bright adult colour. Common Blue damselflies are often a pale pinkish-brown rather than sky-blue on first emergence. Some damselflies, Blue-tailed are a good example and undergo a gradual colour change as they age. The females have several different colour forms, some change from violet to rich brown, others from salmon-pink to blue. Some of the larger dragonflies also change colour as they age. Some old females may start to develop the colouration of the males. Examples are Common Darter, which goes from yellow-brown to reddish brown, and Black-tailed Skimmer, which goes from yellow-brown to a blueish-grey.
Greatly simplified, the life cycle is Egg (usually laid under water), Larva (free moving, water dwelling nymph) and Adult.
The larva lives for several weeks (or years depending on species) underwater and undergoes a series of moults as it grows. It emerges from the water when it is ready to undergo its final moult where the "skin" splits to release the winged adult; much as a Butterfly or Moth emerges from its pupa.
Mainly, adult dragonflies eat other flying insects, particularly midges and mosquitoes. They also will take butterflies, moths and smaller dragonflies. There is one Asian species which takes spiders from their webs!
The larvae, which live in water, eat almost anything living that is smaller than themselves. The larger dragonfly larvae are known to catch and eat small fish or fry. Usually they eat bloodworms or other aquatic insect larvae.
Dragonflies certainly do eat large numbers of flying pest species, but using them to control these pests is not really feasible. There have been a number of studies carried out and only in very restricted and tightly controlled environments have Dragonflies, or their larvae, been shown to be able to control pest numbers. In the open, there is no reason to suppose that Dragonflies introduced to a pest rich habitat will stay there. Indeed, they certainly will not if other aspects of the environment do not suit them. It follows from this that your best chance of getting Dragonflies to prey on pests is to develop the habitat so that it is particularly suitable for Dragonflies, a worthwhile aim in itself! See the BDS publications "Dig a Pond for Dragonflies" and "Managing Habitats for Dragonflies" for more details of how to do this.
Dragonflies do have enemies. Among the species that catch and eat adult dragonflies and damselflies are birds (e.g. Wagtails and Hobbies), Spiders (many damselflies are caught in webs), Frogs, and larger species of dragonflies (which catch and eat other dragonflies and damselflies). In the larval stage, which is spent underwater, they are preyed on by fish, frogs, toads and newts, other water invertebrates - and Kingfishers (see photo below).
Their defences include their excellent eyesight and flying skills which can help them to evade capture. Some are coloured black and yellow, or black and red, which is the universal warning colouration and may deter some of the bird predators.
There are many legends and myths about dragonflies and damselflies from all parts of the world. Many are evident from their common nicknames. In the UK, Dragonflies were called 'Horse-Stingers'. This name may come from the way a captured dragonfly curls its abdomen as if in an attempt to sting. Another possible explanation of this name is that the big Aeshnids etc. are/were often seen flying round horses in fields. Here they were actually feeding on the flies attracted to the horses. Occasionally a fly would irritate/bite a horse enough to make it twitch or skip about. People seeing it made the inference that it was the dragon, being big and obvious, stinging, rather than an unseen fly biting.
An old name for damselflies was 'Devil's Darning Needles'. This stems from an old myth that if you went to sleep by a stream on a summer's day, damselflies would use their long, thin bodies to sew your eyelids shut! Naturally there is no truth in either myth
Similar myths are found throughout the world. You can find more about them by visiting Cultural Odonatology References, a site which has reference material relating to myths, legends, folklore and cultural significance of Odonata throughout the world. For more myths, and mythical names used in Europe you could visit Swedish Dragonflies where you will find a page of such items. (Both these links will open in a new window.)
Yes, Dragonflies do have a pair of antennae. They are very tiny and difficult to see. If you look at the photo on the right you will just be able to see the antennae between the front of the eye and the front of the face of this Emperor dragonfly. As dragonflies rely much more on their eyesight than on a sense of touch or smell, they do not need the large antennae found on some beetles and moths.
Several species of dragonfly are known to collect in large aggregations or swarms. In Europe, the Migrant Hawker (Aeshna mixta) and the Four-spotted Chaser (Libellula quadrimaculata) have been observed to do this. In most cases this appears to be due to very favourable feeding conditions in the locality. It may also be a "courting" group with males actively searching for females. This is less likely as males are much more aggressive to each other when looking for a mate.
The Four-spotted Chaser occasionally collects in these large aggregations before making a mass movement to another locality (like a bird migration). The reasons for this are unclear but may be due to population pressures. There are records from the US of migratory assemblages of species such as the Green Darner (Anax junius) and various species of Saddlebags (Tramea).