Dragonfly eats scale insect, video

This September 2017 video shows a male brown hawker dragonfly eating a scale insect.

Hennie Tholen made this video in a backyard in the Netherlands.


What dragonflies eat, new study

This video says about itself:

The Secret World of Dragonflies | Short Film Showcase

17 December 2014

The colorful, acrobatic dragonfly may seem familiar, but this stunning macro film reveals the mysteries behind its metamorphic life cycle—and some surprising adaptations.

See more from filmmaker Andy Holt here.

Learn about the making of this film here.

From the University of Turku in Finland:

What is on the menu for dragonflies

October 3, 2017

Researchers from the Universities of Turku and Helsinki, Finland, are the first in the world to discover which species adult dragonflies and damselflies prey upon, as modern laboratory techniques enabled the study of the insects’ diet. In the study, prey DNA was extracted from the tiny dragonfly droppings and the researchers managed to identify dozens of prey species from the samples. The results shed light on dragonflies’ position in natural food webs with an unprecedented specificity.

Dragonflies and damselflies, i.e. the odonates, are numerous and quite large insects. As adults, they control the air space as the apex predators of invertebrates. However, the diet of dragonflies has never been resolved comprehensively as it is difficult to observe them catching or eating their prey. Now for the first time, a research group led by Finnish scientists has established which insects the adult dragonflies prey on.

The dragonflies’ menu was studied by extracting and identifying the DNA of prey species from faecal samples. With this method, the researchers were able to identify in detail which insects the three studied dragonfly species had eaten and a large group of different prey species was identified as their prey. At the same time, the researchers discovered that the three dragonfly species prey upon practically the same species — and that they share their diet with birds and bats which are the dominant vertebrate predators.

The research group included researchers from the Biodiversity Unit of the University of Turku, the Department of Agricultural Sciences of the University of Helsinki, and Swedish University of Agricultural Sciences.

This study is very significant as dragonflies are at the top of the insect food webs all over the world and regulate the number of many other insect species. Therefore, it is important to know exactly which species they eat. From there, we can, for example, assess the dragonflies’ impact on the populations of those insects that are harmful to humans. Yet so far, the information on the diet of adult dragonflies has practically been based on individual visual observations of their prey, says Researcher and leader of the research group Kari Kaunisto from the Biodiversity Unit of the University of Turku.

In the study, the researchers also tested the applicability of different methods for extracting DNA, and their results can be utilised in future research.

When Kari told me of his idea, I was immediately interested. It was surprising that no one had done this before and I accepted the challenge at once. Often in research, earlier studies provide a starting point for laboratory work, but in this case we had to start from the beginning. In a new project, it’s a good idea to test different methods and we wanted to lay a good foundation for future studies, says researcher Eero Vesterinen from the University of Helsinki, who in his earlier research has specialised in the research of feeding biology, especially by applying molecular research methods based on DNA.

As dragonflies are large insects, they have long interested researchers as well as nature lovers. The number of the odonate species is relatively small and identifying different species is easier than with other insect groups. Dragonflies are excellent model species for biological research also because they give indications of the state of both terrestrial and aquatic environments. Dragonflies spend their larval phase in water, after which they control the air space as the flying apex predators of invertebrates. The new study sheds additional light on dragonflies‘ role in the aerial food web, notes Professor of Insect Ecology Tomas Roslin from the Swedish University of Agricultural Sciences, who also participated in the study.

The study was recently published in the international Ecology and Evolution journal.

Banded darter dragonfly video

This 17 August 2017 video is about a banded darter dragonfly cleaning itself.

Chris Ruijter in the Netherlands made this video.

Black-tailed skimmer dragonfly female photo

Black-tailed skimmer dragonfly female, 25 July 2017

This photo shows a black-tailed skimmer dragonfly female, in the Gooilust nature reserve in the Netherlands on 25 July 2017.

Males of this species are light blue and black. Females are yellowish, later brownish.

Dragonfly Week in Britain

This video from Britain says about itself:

Dragonfly Week 2017

2 July 2017

A look back at Dragonfly Week 2016 at WWT London Wetlands. This year it will be 15th-23rd July and the British Dragonfly Society will be there to offer expert info and advice. Take the Dragonfly Challenge while you’re there!

By Peter Frost in Britain:

Dragons in the sky, near you

Friday 21st July 2017

As it is national Dragonfly Week PETER FROST investigates these complex, intriguing and, at the same time, beautiful insects bequeathed to us by most distant prehistory

“I saw, once, an endless procession, just over an area of water-lilies, of small sapphire dragonflies, a continuous play of blue gauze over the snowy flowers above the sun-glassy water. It was all confined, in true dragonfly fashion, to one small space. It was a continuous turning and returning, an endless darting, poising, striking and hovering, so swift that it was often lost in sunlight.”

That was Northamptonshire born novelist HE Bates writing in 1937 — in his series of nature essays Down the River — in what have been described as endless summers as dark war clouds gathered over Europe.

Bates would become much better known for his wartime books such as Fair Stood the Wind for France and after the war for his Darling Buds of May novella and sequels that became the hugely popular TV series.

While ambling beside your favourite canal towpath, riverside walk or village pond there’s nothing like the colourful, iridescent flash of a dragonfly to tell you that summer is here.

This is national Dragonfly Week and this Sunday July 23 there is a special dragonfly event at the National Trust’s Wicken Fen in Cambridgeshire. You can join experts to learn more about some of our most spectacular wildlife.

There are 57 recorded species of Odonata in Britain, made up of 21 damselflies and 36 dragonflies.

Damselflies are smaller and weaker flying relatives of dragonflies.

So what is the main difference between a dragon and a damsel? The most noticeable is that most dragonflies rest with their wings open while damselflies rest with their wings folded together over their body. Damselflies are also weak fliers and tend to stay close to water.

The loss of garden ponds, concreting over the countryside and intensive farming has already lost us at least three species in the last 45 years and more are under threat.

The insects are also extremely sensitive to the weather and find it difficult to adapt to climate change.

The National Trust is so concerned about the issue that in 2009 it opened the UK’s first Dragonfly Centre at Wicken Fen in Cambridgeshire in order to create wetland habitats where rare species can be protected and studied.

Chris Packham — the often outspoken BBC Springwatch presenter — told us more species could be lost without action: “The loss of wetland habitat throughout the UK is having a massive impact on the long-term survival prospects for many dragonfly species.”

Adult dragonflies are amazing creatures with huge multifaceted compound eyes each made up of nearly 24,000 individual ommatidia or simple eyes.

They have two pairs of strong, transparent wings, sometimes with coloured patches, and an elongated often amazingly colourful and iridescent body. They are remarkably agile fliers.

Some of our native dragonflies are really large. In Britain some such as the Emperor and Brown Hawker reach a length of about 85mm (3.5in) and a wingspan of over 120 mm (5in).

Fossil evidence shows there were once dragonflies with wingspans up to about 750mm (30in). They first appeared between 250 and 300 million years ago and they have changed very little since then.

They are are fierce predators both in their aquatic larval stage — when they are known as nymphs or naiads — and as adults. Several years of their lives are spent as nymphs living in fresh water. The adults may be on the wing for just a few days or weeks.

They have a uniquely complex sex life involving indirect insemination, delayed fertilisation and sperm competition.

During mating, the male grasps the female at the back of the head or on the prothorax and the female curls her abdomen under her body to pick up sperm from the male’s secondary genitalia at the front of his abdomen.

Romantically the two curved bodies can form a heart shape while the actual coupling takes place.

Dragonflies are some of the swiftest flying insects, with hawker dragonflies recorded at a top speed of over 20 miles an hour. They also display high manoeuvrability with some species capable of hovering and even flying backwards.

With their giant complex eyes dragonflies live in a world highly influenced by sight. The shape of those 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.

As well as the main two large eyes, they have three more located on the top of their heads in a triangle formation. These are simpler and 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 while completing complex flight patterns.

Rather than being designed for walking dragonfly’s legs are positioned to catch prey in mid-air. Once a meal is trapped, the dragonfly’s forward facing legs are capable of holding up the prey item to its mandibles.

They eat small flying insects such as flies and mosquitoes — as well as butterflies and even smaller fellow dragonflies.

Their aquatic larvae are voracious, hunting various invertebrates, as well as tadpoles and even small fish. They alter their colouration between moults to blend in with their surrounding environment which helps them to stay hidden away from predators and prey too.

Want to help our British dragonflies? Or just find out more about them? The British Dragonfly Society is the place to start.

New research has shown how a dragonfly’s brain anticipates the movement of its prey, enabling it to hunt successfully. This knowledge could lead to innovations in fields such as robot vision: here.

South American blue dragonflies, new study

This 201 video fgrom Brazil is called Zenithoptera lanei male and female. By Ruy Penalva.

From Science News:

The blue wings of this dragonfly may be surprisingly alive

Adults go to great lengths to shine blue

By Susan Milius

7:00am, June 30, 2017

An adult insect wing is basically dead.

So what in the world were tiny respiratory channels doing in a wing membrane of a morpho dragonfly?

Rhainer Guillermo Ferreira was so jolted by a scanning electron microscope image showing what looked like skinny, branching tracheal tubes in a morpho wing that he called in another entomologist for a second opinion. Guillermo Ferreira, then at Kiel University in Germany, showed the image to a colleague who also was “shocked,” he remembers. A third entomologist was called in. Shock all around.

The shimmering, bluest-of-skies wings of male Zenithoptera dragonflies might be unexpectedly and fully alive, Guillermo Ferreira says. That bold idea will take some testing. So for now, he and colleagues report the unusual tracheal respiratory system, the first in any insect wing as far as they know, in the May Biology Letters.

Wings of insects start as living tissue, but as the creatures take their adult form, cells die between the strut work of supporting wing veins. The dried-out zones can go cellophane-clear or cover themselves in color, bordered by the vein network like the glass pieces in a cathedral window. The veins, as they’re called, have their own respiratory tubes, nerves and such. But entomologists thought the rest of an insect wing would be no more alive and in need of oxygen than toenail clippings.

Living, breathing wings might help explain how South America’s four or five species of morpho dragonflies make such complicated blue color, says Guillermo Ferreira, now at the Federal University of São Carlos in Brazil. Blue pigment, rare in nature, is nowhere on these wings. Instead, the wings, perhaps powered by abundant oxygen, create a living layer cake of light-manipulating doodads.

In the tough inner layers, male Z. lanei wings form nanoscale spheres sandwiched between blankets of black pigment–filled nanolayers. This setup can enhance reflections of blue light and muddle other wavelengths. On top are two more light-trick layers, each made of wax crystals. The uppermost crystals, Guillermo Ferreira found, are shaped “like little leaves.”

Better blues might help a male intimidate rivals for breeding territory around the edges of their palm tree swamp homeland. Male dragonflies don’t just dart and bluff. Guillermo Ferreira often sees a male “rushing toward the rival, grabbing the wings, biting the wings and then sometimes biting the head.”

In spite of the world-class color nanogadgetry, males aren’t known for courtship displays, he says. “The female just flies in, and he just grabs her.”