Whilst ambling along your favourite riverside walk there’s nothing like the colourful glimpse of a dragonfly to tell you that summer is well and truly here. And though these vibrant insects might feel like a familiar sight, there’s plenty you may not know about them. Here’s a handful of facts that might make you see these winged wonders in a different light.
1) Dragonflies are ancient in design
Alongside mayflies, dragonflies originate from the most ancient group of insects called “Palaeoptera”. Their ancestors are some of the largest flying insects in history and would have flown over carboniferous forests 300 million years ago. One group, the Meganeuridae, had an immense wingspan of 70cm - imagine finding that in your garden! The first true dragonflies appeared a little later, 250 million years ago, and by this time in history a large number of the modern dragonfly taxonomic families were formed.
2) They are super agile in flight
Dragonflies are of some of the swiftest flying insects, with hawker dragonflies recorded at a top speed of around 36 km an hour. This speed is achieved using their hefty flight muscles which are found on the thorax walls. Not only that, but they are highly manoeuvrable, with some species capable of hovering and even flying backwards. Dragonflies achieve a hovering flight by coordinating their head, thorax and wing movements, aided by a specialised group of hairs around their head and neck that work to keep the head steady. This stability of the head position whilst hovering improves the dragonfly’s vision in flight as they look for food or mating opportunities.
"As their giant eyes might suggest, dragonflies live in a world highly influenced by sight."
3) They have incredible eye sight
As their giant eyes might suggest, dragonflies live in a world highly influenced by sight. The impressive size and shape of their eyes allows them to see ahead, behind and to the side all at once. They also have great colour vision, which enables them to spot each other. In addition to their two large eyes, they have three more located on the top of their heads in a triangle formation. These simple eyes detect very little detail and are specifically attuned to light intensity. This ability allows the three eyes to detect information to assist flight, such as altitude and orientation whilst completing complex flight patterns.
4) Their legs aren’t made for walking
Though typically a useful solution to get around, the legs of adult dragonflies are used for a different purpose. The thoracic segment attached to their mid and hind legs (called a synthorax) is tilted forwards, angling the legs forwards as well. This makes the legs poorly suited for walking but positioned well to catch prey whilst airborne. Once a meal is caught, the dragonfly’s forward facing legs are capable of holding up the prey item to its mandibles. Typical prey items include small flying insects such as flies and mosquitoes – as well as some larger item such as butterflies and even small dragonflies.
5) As juveniles, they are ambush predators
The aquatic larvae of dragonflies are voracious, attempting to hunt many species. They lie in wait amongst the sediment and vegetation until some unwitting prey ventures past. They will feed on various invertebrates, as well as tadpoles and even small fish. When the larvae detect movement they will strike fast, using their jaws to grab hold of their prey. Dragonfly larvae also have an additional talent; they are able to alter their colouration between moults to better blend in with their surrounding environment. This skill helps them to stay hidden away from predators and prey too.
Want to help out our British dragonflies?
There’s a simple way to do just that. This coming week from the 15th to the 23rd of July the British Dragonfly Society is running a citizen science project called the . They are inviting people to choose one day this week to spend some time recording dragonfly species at your local wetland, pond or river, and to record the information on their spotter’s sheet. Not sure which species they are? Find out .