Insect of the week: what do red dragonflies mean?

By Kim Pullen and Chris McKay

A city-dwelling Australian in the southern parts of the country might look to the calendar to see what season they’re in. First of March? It must be autumn. But beyond perhaps packing a jumper as we walk out the door, we don’t tend to change our behaviour all that much. We’re largely disconnected from the direct effects of nature.

Plants, animals and fungi don’t take their cues from the Gregorian calendar; they change in response to shifts in temperature, moisture in its various forms and length of day, as well as inherent factors in the organism. Certain fruits will ripen, some animals will produce young, while other animals change form or disappear.

When your day-to-day economy is intimately connected with the surrounding natural environment, it pays to take note of these changes. The Gooniyandi people of the Fitzroy Valley in the tropical Kimberley region of Western Australia look to the weather and changes in the behaviour of animals and plants to know what time of year it is and the resources that are available to them. Red dragonflies, commonly known as Scarlet Percher dragonflies, or Jarloomboo to the Gooniyandi, announce the start of Moonnggoowarla—the dry season and cold weather time.

The Scarlet Percher, or Jarloomboo, is an indicator of seasonal change in the Fitzroy Valley, WA. Bill & Mark Bell/Flickr

The temperature through the year doesn’t change greatly on the Fitzroy—it is nearly always warm by southern standards. What does change is the rain, with nearly all of it coming down in the short, sharp summer ‘wet season’. Water is important to a dragonfly, because for a large part of its life it lives in a stream or lake as a predatory nymph or ‘naiad’. When fully grown, this creature crawls out of the water and its skin splits to release a properly formed dragonfly, pale and shrivelled at first but soon in the air after expanding and drying its wings in the sun.

When Gooniyandi see Jarloomboo they know that the swordfish (Galwanyi) are fat. The fat of swordfish is very soothing to Gooniyandi, healing their aches and pains, and the soft meat is very good for children to eat.

Members of Muludja community in the Fitzroy Valley worked with CSIRO to produce their own calendar—the Gooniyandi Seasons Calendar—a wealth of Indigenous ecological knowledge. The development of the calendar was driven by a community desire to document seasonal-specific knowledge of the Margaret and Fitzroy Rivers in the Kimberley, including the environmental indicators that act as cues for bush tucker collection. The calendar also addresses community concern about the loss of traditional knowledge.

On the Fitzroy, the appearance of red dragonflies is a much better indicator of the march of seasons than a glance at the old wall calendar.

Insect of the week: attack of the giant bugs

Ladies and gentlemen, we interrupt our program of blog posts to bring you a special bulletin from the nation’s capital, Canberra.

Giant bugs have been spotted in the parliamentary triangle area of Canberra and appear to be crawling over the Questacon building…

Giants bugs spotted on the Questacon building in Canberra

No, it is not an extraterrestrial invasion, nor even the set of a B-grade 1950s horror film—but Canberra residents out at night this week could be excused for thinking they had stumbled onto one.

These giant bugs are some of the many artworks being projected onto prominent buildings around the city at night as part of the Enlighten: see Canberra in a whole new light festival.

Insect specimens from CSIRO’s Australian National Insect Collection are playing a starring role in the festival—bee, Christmas beetle, cicada, jewel beetle and palm weevil specimens were among the models used for the projected artworks.

The artworks in question are the creations of CSIRO Science Art Fellow, Professor Eleanor Gates-Stuart. Working with 3D reconstruction and modelling specialist, Dr Chuong Nguyen of CSIRO’s Mathematics, Informatics and Statistics division, she has managed to transform the lifeless insect specimens into vibrant photonic reincarnations.

Chuong used a state of the art 3D scanner to capture the insect specimens in 3D and then Eleanor used the scans to create an animated, bug-inspired artwork. Large scale projection specialists, The Electric Canvas, worked with Eleanor to convert still frames from her animated artworks into architectural projections, and voilà… the results are stunning.

Eleanor and Choung work their magic on the insect specimens

ABC’s 7.30 program interviewed Eleanor about her work as part of the festival and caught some footage of Chuong and the 3D scanner in action. Watch the segment here (from 2:35).

You can find out more about Eleanor’s work on her website.

The festival runs until Saturday 9 March, so if you’re in Canberra go along and check out the giant bugs while you still can.

And by the way, these bugs are completely harmless so don’t do a Kent Brockman and pledge your allegiance to the insect overlords…

Insect of the week: Insects in a burning land

By Kim Pullen – Australian National Insect Collection

The bushfires moving through the Australian landscape this summer have given us a stark reminder of the impact they have on people, property and livestock. Less visible is the toll on native animals, and even less the impact on insect life.

Have you ever wondered what happens to insects in a bushfire?

The bushfires in Tasmania in January left a path of destruction. ToniFish/Flickr

You probably figure their chances of survival are pretty slim, and yes, there will be many insects that don’t survive a fire event. But fire has been a feature of the Australian landscape for millennia and many insects have found a way to thrive here regardless. So, how do they do it?

The truth is that for many insects we still don’t know—we are working on it but it’s not an easy task. Here’s some our previous research.

For example, we may have information about which species managed to survive a fire event of a known intensity and we can compare that to the insects found in a similar area nearby that hasn’t been burnt, a refuge, to draw some conclusions about an insect’s resilience. But even if our results lead to strong conclusions for that particular area and for that particular fire intensity, we need to be wary of extending those conclusions to other regions, even other nearby sites, or to different insects and fires of different intensities. To get a better picture, we would need to do a number of studies of different ‘fire variables’ and see if a pattern emerges. The fire variables that influence the survival of insects include intensity, season, area burned and the interval between fires.

The insects most vulnerable to fire are those living in the vegetation and leaf litter on the soil surface. From the vegetation, some may be able to fly away to an unburnt area, or may be blown clear by the wind, giving them a chance at survival. Insects that bore into stems or tree trunks may also survive a fire if it isn’t too hot. Those that live in the soil are quite well protected and may fare better in a fire. But even if they survive the fire, many soil-dwelling species also spend part of their life in the open. So, when they emerge from the soil they may find that the fire has left them without shelter from predators and with nothing to eat.

As the vegetation in a burnt area recovers, it will be recolonised by insects (and other animals) from refuge areas. How fast this happens will depend on things such as how far away the refuges are and how mobile a particular species of insect is. Good flyers like butterflies and the larger wasps and flies can recolonise a suitable area quite rapidly and small flying insects can get carried in on the wind. A flightless beetle that lives in leaf litter may be a very slow coloniser.

The fire beetle is dependent of fire for survival. Image: Jiri Lochman, Lochman Transparencies

And then there are some insects that are quite fond of fire, dependent on it in fact. The ‘fire beetle’, Merimna atrata, didn’t get its name by accident. It is attracted to bushfires and even camp fires; in fact it even looks burnt. The larvae of the fire beetle develop in burnt wood so it has developed a way to seek out a fire. It has two pairs of infrared sensors in its abdomen, packed with nerve endings, which alert the beetle to a fire.

The flies of March are upon us

Anyone who’s come into contact with a March fly, also known as a horse fly, is not likely to be very welcoming to the next one they come across.

March flies, common across southern Australia during summer, are known for their short, sharp and stinging bite. Many a time have I felt the shock of a bite on my leg and then been surprised when I look down to find the culprit is a fly—and still sitting there by the way.

I thought the incessant buzzing of the flies in summer was bad enough, but now they’re biting us as well?

The March fly’s bite can deliver quite a sting. dracophylla/Flickr

Dr David Yeates, the director of CSIRO’s Australian National Insect Collection and an expert on flies (Diptera), says that the March flies are after our blood. Just like a mosquito, the female March fly bites us to get at our blood. It then uses the protein in the blood to develop eggs, which give rise to the next generation of March flies.

So I guess that explains why they are so insistent.

Dr Yeates says that the painful and itchy reaction that can follow a bite is caused by the anticoagulants the fly injects us with when feeding on our blood. The anticoagulants are chemicals in the fly’s saliva that prevent our blood from clotting and ensure a steady flow for them to feed on—again, this is similar to a mosquito.

There are about 400 species of March fly in Australia. Some of these feed on flower nectar and pollen but the majority prefer a helping of blood.

March flies are not too picky about where the blood comes from either; if you’re warm blooded then you’re a target. Horses come in for quite a bit of attention, hence why the flies are also known as horse flies. Dr Yeates says that in North Queensland the flies have even been seen feeding on Crocodiles!

Dr Yeates was recently interviewed by the ABC about March flies, read the interview.

Christmas Beetles! The season is the reason

By Kim Pullen – Australian National Insect Collection

Christmas beetles, the quintessential insect of the summer festive season, have arrived.

Sporting their resplendent burnished bronze backs under the summer sun, these bulky creatures home in on the tops of gum trees with their loud whirring and clumsily try to grab a foothold, often only to tumble down and get up again for another try.

Christmas beetles clinging on for a leafy feed. Anoplognathus (Scarabaeidae) are common in southeastern Australia.

By the time you see a Christmas beetle, it’s nearly at the end of its life. It has already spent almost a year in the soil as a grub, eating organic matter, grass roots and possibly the finer surface roots of gum trees. In times of drought in south-eastern Australia, a grub may be forced to stretch out its life cycle and go another whole year in the soil!

A swarm of Christmas beetles can eat a lot of leaves, but they are not usually worth trying to control—the beetles you manage to get rid of one day will probably just be replaced by others the next. And in any case, the infestation does not last long.

In the ‘State of Origin’ of Christmas beetle colours, the Queenslanders hold the title. The Christmas beetles familiar to Victorians and New South Welshpeople (that’s a word right?) may be pretty, but they don’t compare to their tropical Queensland cousins. The Queensland rainforest dwellers come in smooth gold, pitted dark green, violet and even a mysterious iridescent opal with mauve reflections. The shifting colours are structural, coming not from pigments but from multilayer reflectors built into the hard shell of the beetle—more on this here.

Looking postively festive: a Christmas beetle from tropical Queensland shows off its jewel-like colour.

This Queesland enthusiast has photographed a whole range of colours among his local Chrissy beetles.

So enjoy your Christmas beetles this year and tune in to Insect of the Week again next year for many more tales from the Insect world.

Walking on water… a miracle?

By Kim Pullen – Australian National Insect Collection

Walking on water might seem like a miracle to us mere humans but for some insects it’s part of their daily comings and goings. Water striders, bugs of the family Gerridae, are amongst the best in business.

The water strider has no problem walking on water. Image: Paul Zborowski.

So how do they do it? Water striders take advantage of the properties of surface tension of liquids. Because the water molecules at the surface don’t have any neighbouring water molecules directly above them, they have a higher energy, and the surface essentially pushes back against anything pressing down on it—such as the water strider’s feet.

It just isn’t heavy enough to break through surface of the water. Image: Wikimedia Commons

Of course, a heavy object—like, say, a human—will overcome surface tension and fall right through. This insect is light enough that it won’t and the water-repellant hairs on its legs and under its body help further.

We have an experiment that will help you explore surface tension for yourself.

Water striders usually live in groups, and skate across the surface using a rowing motion of their legs. Watch one skate here:

They attack other small creatures on the surface, including anything that falls into the water. They can detect the tiny ripples from a distressed insect, and go after it. Some water striders also produce their own coded ripples to court mates or warn competitors away.

A water strider takes a break from water walking. Image: Paul Zborowski.

The world’s oceans are practically devoid of insects; the marine habitat is one of the few that insects have not exploited. One exception is the tropical sea skaters, water striders of the genus Halobates. Some sea skaters are coastal, feeding (like their freshwater cousins) on wayward insects. The truly oceanic species never see land, and eat plankton.