How many legs is enough?
There are creepy crawlies out there with many legs. Centipedes (from the Latin centi meaning hundred and pedis meaning foot) and millipedes (from the Latin milli meaning thousand) do not literally live up to their names, but they certainly have many pairs of legs.
But how many legs does a caterpillar have (see photos)? Being insects caterpillars have six legs but appear to have a lot more. The six ‘true’ legs are those situated on the thorax near the head. The other leg-like appendages are called prolegs and are used for walking and clinging.
Most caterpillars have a pair of anal prolegs (known as claspers) at the end of their bodies and several pairs of medial prolegs half way down their bodies. Each proleg contains a series of hooks. When the caterpillar is moving fluid is pumped into the proleg to expand the hooks. Once the proleg hits the surface the fluid pressure is released and the hook closes attaching the caterpillar to the surface.
For caterpillars the difference between a ‘true’ leg and a proleg is that the former is jointed into five segments whereas the proleg is a fleshy structure with minimal musculature.
Other insect larvae also have prolegs. The larvae of sawflies (called spitfires) have prolegs on each abdominal segment, a minimum of six pairs.
Imagine tying your shoe-laces.
Funeral for a friend
Sometime animal behaviour seems almost human.
I was sitting outside watching the landscape change colour during ‘golden light’ time when I heard a loud squawk and an Australian Magpie (Gymnorhina tibicen) fell out of a nearby tree and landed on its back. It gave three feeble flaps of its wings and then died on the spot. Scanning the branches there was no sign of a snake, goanna or other reason for its demise.
Almost immediately another magpie flew down to the body and gave a loud, raucous call. In response about a dozen magpies arrived and formed a rough circle around the body. One by one each magpie approached the body looked down at it for a few seconds and then wandered off to do its magpie thing.
I am loathe to attribute anything anthropomorphic to the scene but it did seem like I was witness to a ritual of some sort…. and that felt ok.
The Emperor’s New Clothes
The Emperor Gum Moth (Austrocaligula eucalypti) – previously Opodiphthera eucalypti, pictured below is one of our largest summer moths. Like all butterflies and moths its lifecycle consists of four major steps – egg, larva (known as a caterpillar), pupa and adult. This is known as complete metamorphosis (i.e. incorporates all four steps). Some insects undergo fewer steps in their lifecycle e.g. grasshoppers and cockroaches. This is termed incomplete metamorphosis.
During the larval stage, caterpillars grow and then have to moult as they become too large for their skins. Emperor Gum Moth caterpillars go through five such stages. In many caterpillars, each stage or instar looks like the previous one only bigger. However the Emperor Gum Moth caterpillar changes its livery with every moult.
The first instars are almost entirely black, pictured above right. With successive moults the caterpillars become more colourful and develop the characteristic tubercules and spikes. Last week I discovered young gums trees festooned with 3rd stage instars, pictured above left. During the fifth (last) stage the caterpillar takes on the familiar lime-green colour with a yellow stripe (pictured left).
The Emperor does indeed have new clothes.
Reflections on Ten Years
I have been living in Yea for ten years taking notes on bird populations. It is endlessly fascinating to watch the seasonal flow of bird populations.
- The creaky Gang-gangs that drop in for a few weeks,
- The majestic Yellow-tailed Black Cockatoos that visit with their ponderous looping flight
- The feverish calling of Rufous Whistlers and Yellow-faced honeyeaters that begins in September and continues over Summer
- The arrival of cuckoos and kingfishers
- The fleets of ducklings trailing behind watchful parent Wood Ducks or Black Ducks.
However, it saddens me that I have witnessed in this short period a clear decline in some once-common birds. The Willie Wagtail was often considered the most ubiquitous bird in Australia – easily observed from every highway in Australia. It’s getting hard to find them around the district now. Their cheery call, sometimes described as “Sweet-and-pretty-little-creature” can sometimes extend into the night time in Spring and they should be companions in every farm and park. Why are they declining? One factor is the increased presence of Pied Currawongs which ruthlessly predate their nests and eat the chicks. This large scavenger used to spend warm seasons in the high country and only roam lowland towns between May and September. Now they are present all year (some researchers name 1985 as the first year of their refusal to migrate) and could well be a primary cause of decline in many small bird populations. Incidentally, Currawongs also eat berries of weeds like Privet, Hawthorn and Cottoneaster, contributing to their dispersal. They do control destructive insects in the forest as well, so they are not all bad.
Magpie larks are also declining. Once an annual event in Yea Wetlands, the construction of their unique mud bowl nest has ceased. They can still be found around the district but in smaller numbers. I used to love the arrival of Scarlet Robins around the farming district each Winter, I rarely see them now. However, the Flame Robin seems to have increased in number to compensate.
When i first bought my house in Yea, we had a resident Boobook owl whose roost could be discovered by following the outraged calls of small birds that love to mob owls when they are discovered in their territory. Owls have become seriously rare. Some commentators blame rat poison – Ratsak changed their formula to a faster-acting chemical that results in the death of owls that eat the dying rat.
It has been good to watch White-faced Herons and Australian Ravens become customary breeders in Yea Wetlands. This has only been the last few years, they were rarely seen there in 2014. But back then, Australasian Swamphens and Great Egrets were more common and now they are rarely seen. I think these reflect local variation not population decline. When conditions are right they should return.
I note that, this year, the Northern visitors that were seldom seen have been more common – Noisy Friarbirds and Blue-faced honeyeaters have both been breeding here. There were no lorikeets in Yea ten years ago; Rainbow Lorikeets are now resident.
The first thing I did in my house in Yea was to plant locally-native plants in the garden and reduce the dominance of useless introduced plants like Kikuyu grass, English box or Photinia hedges. These plants, along with flaxes, agapanthus, palms and pittosporum attract no insects, are boring to most wildlife and produce desert conditions for birds. It is such a joy to see the return of pollinators and many small birds to my revegetated small urban block.
These ten years have been wonderful indeed, and I am sad as I prepare to leave Yea and move to Warragul. I take with me a suitcase of great experiences and precious friendships from which I hope to draw to enrich the new community I will call home.
Lifecycle in five pictures
The Dotted Paropsine Leaf Beetle (Paropsis atomaria), pictured below, is one of many species of Eucalyptus Beetle feeding on our gum trees at the moment. Atomaria refers to the speckled colours on the wing cases.
After mating tubular eggs are laid in a cluster around a gum twig by the female beetle. The larvae when hatched are yellow with a black head and tail and covered in small black dots.
Both the adult and larval forms are herbaceous. The larvae form groups that entirely devour young gum leaves. They pupate in the ground and emerge as adults, which feed on more mature leaves, creating semi-circular shapes in the leaf margins.
The many species of Leaf Beetle come in a range of colours. At this time of the year they provide welcome mobile tree decorations – unless you are a tree grower!
Koel Calling
A few people contacted me this week about a strange bird-call ringing constantly from various places in Yea.
The call is an Eastern Koel Eudynamis orientalis– a type of large cuckoo. The male is black, the female is mottled brown. During the breeding season the male calls loudly and incessantly, day and night, so to hear this bird call while it visited Yea was not difficult. In Queensland they are sometimes called the Brainfever Bird because they don’t let up and people can’t sleep.
And visit Yea it did. They spend Winter in New Guinea or Indonesia where they are mostly silent and migrate to Australia for breeding, usually confining their visit to Queensland and northern NSW. Lately, individuals have been turning up in Victoria at various places – Benalla, Mallacoota, Melbourne Botanical Gardens. A few years ago I saw one at Melbourne Cemetery. This is the first time one has been recorded in Yea. It doesn’t seem to have stayed very long.
Koels are a large cuckoo and look to lay their egg in open nests of birds such as magpie larks and wattlebirds. I think this one caused no harm because no female was with it. It was just a lonely male crying out to the Universe in the hope of getting a response.
Photo by facebooker Robert Anderson
who stopped in Yea to use the toilets.
Beware of the pointy ends
Eastern Long-necked Turtles (Chelodina longicollis), alternatively known as Snake-necked Turtles are one of 23 species of turtles in Australia (we don’t have any Australian tortoises). During the hot summer months these turtles bury themselves in the mud of dried up water bodies but heavy rain triggers them to migrate over land to find new food sources. Given our current weather it is no surprise then that recently turtles have been on the move – lots of them.
Long-necked turtles can be found in slow moving or still water bodies. A quick trip along the Goulburn River at the moment where a many billabongs have be filled by the recent flooding will reveal many turtles either floating on the surface or sunning themselves on nearby logs (see photo below).
The turtle’s life is not all sun and swimming. In their moves to greener pasture they are often killed crossing roads as they are very slow moving and their colour makes them hard for drivers to see. ‘Helping’ a turtle cross the road is fraught with dangers for the uninitiated. Turtles are carnivorous eating fish, frogs, tadpoles and yabbies using there sharp claws to capture and then tear apart the prey and even though humans are not in their diet they can deliver a painful nip if picked up incorrectly.
If annoyed long-necks can also emit an offensive spray from the anus so when picking up a turtle, orientation is everything. Beware of the pointy ends!
When customs don’t translate
The mating rituals of spiders are quite complex. For web-based spiders such as Orb-weavers it consists of the male spider tapping the web and seeing what response it gets from the female in the centre. For creatures such as Jumping Spiders it is trickier. With its front pair of legs the male spider has to reach over the front of the female and tap it gently on the ‘head’ to see if a favourable response is forthcoming. Sometimes it has to do this a number of times. This is fraught with risk for the male spider. One false move or misinterpretation of the response could mean the male spider becomes dinner.
I was fortunate enough this week to witness such a display between two Threatening Jumping Spiders (Helpis minitabanda). Pictured above is the male spider (right) tapping on the web that the female was sitting under. It took a number of minutes before the female spider came out. What followed was a series of ‘body-taps’ where the male moved in, tapped and then quickly retreated (pictured right) to assess the reaction to his advances. Unfortunately both spiders got annoyed with my watching and jumped away, hopefully to mate in privacy.
After taking a leaf out of the male spider’s ‘How to romance those of the opposite sex’ book I have subsequently found that female humans, particularly complete strangers, respond badly to someone reaching out and tapping them on the head.
P.S. The mating rituals of spiders and other arachnid facts will be the topic of a Strath Creek Landcare Group presentation after the AGM on November 27.
Stark Raven
I don’t mind the wily white-eyed Australian Raven (Taungurung name: Waa or Waang). Too smart to be hit by a car, and a bird that knows and relishes its place in the great landscape of life, ravens are succeeding in urban areas and benefiting from human changes to land use. A pair of Australian Ravens (Corvus coronoides) has successfully nested atop a tall tree in Cummins Lagoon in Yea Wetlands these last three years. In Taungurung culture, each person belonged either to the moiety of Bunjil, the Wedge-tail, or Waang the Raven.
I take some pleasure in the wailing call of the Australian Raven as it wings its way homeward across the valley, because while common here, they generally are not found in Melbourne – Yea, Healesville and just into the Yarra valley and then it is all Little Ravens. We get Little Ravens in our district also. Each Australian capital city features one dominant corvid: the Australian Raven in Sydney, Canberra, Brisbane and Perth. Adelaide and Melbourne feature the Little Raven; Hobart has the Forest Raven – the only corvid in Tasmania. Northern parts of Australia also have two species of Crow, but there are no crows in Victoria. (Crows lack the large hackle feathers on the throat)
| Australian Raven (Corvus coronoides) | Little Raven (Corvus mellori) |
| 50-54cm | 48-52cm |
| Black, with long throat hackles and white eye | Black, with short throat hackles and white eye |
| Call: Arrk, arrrk, aaaaaargh (dying away) Calls holding head horizontal when perched | Call: Ock, ock, ock Shuffles wings with head up as it calls |
| Usually single or in pairs, sedentary | Often in flocks, sometimes up to 100, nomadic |
| Eats carrion, injured animals, insects, urban waste | Spiders, cicadas, crickets, caterpillars, maggots, urban waste |
| Benefit: cleans up dead things and rubbish | Benefit: helps control flies and insects, cleans up waste |
| Problem: merciless to injured lambs | Problem: None really |
You will notice that ravens do not eat grain. American crows on the other hand invade newly-planted fields prompting the invention of the ‘Scare-crow’. Aussies need a ‘Scare-corella’.
Ravens were traditionally hated by farmers but intensive research has shown that killing healthy lambs is rare. However, the Australian Raven (not the Little) may hover menacingly around a newborn lamb and will eat the afterbirth, the newborn’s faeces (which are apparently high in protein – yes, but not for me, thanks) and any still-born or sick lamb.
For a long time, the birding world thought there was only one species of raven in Southern Australia, but in the 1960s, a great birder named Ian Rowley worked out there were two. It happened like this: he could so imitate the call of the raven that wild ravens would come quite close when he called. One day he and a co-worker approached a tree with two ravens in it and the call was made. The birds in the tree showed no interest whatsoever but some other ravens from a distant tree flew over. They reasoned that there were two species and each had a distinctive call. Later DNA studies confirmed the observation.
Similarly, I noticed that my children never came when I called them by the wrong name. Come to think of it, they seldom came when I called them by the right name.
Sugar sugar Ant
I have this party trick that I like to show off with to amuse the children. When I see a teeming nest of either meat ants or sugar ants, I place my hand on the ground amongst them and let them run all over it. For the little-known surprising fact is that those two types of ants do not sting. They might nip a little but it’s barely discernible; they have no poison to inject into you. The trick is to be confident about the ID before you try this at home, because there are certainly bullants out there who would give that intruding hand an almighty painful sting!
This nest of sugar ants ( Campanotus species) pictured lives under my house and is mainly nocturnal. They only came streaming out in the middle of the day because I pulled a weed that was growing near their nest entrance which must have caused them much alarm. They ran all over my hand and you can see the jaws, but they pose no threat. I believe they are the Banded Sugar Ant (Campranotus consobrinus), the commonest sugar ant in south-east Australia.
Sugar ants are orange with a black head and a black abdomen. Their nest is quite different to the teeming mound with multiple holes that characterises the meat ant (Iridomyrmex purpureus), They usually nest under a rock or under a log sometimes with multiple holes leading into the breeding chamber. The ones at my place seem to mound up around the entrance when rain is coming. My hand is close to the entrance in the middle photo but the disturbed ground (from weeding!) makes it hard to discern.
How does the nest get established? On some balmy hot summer night, a stream of queens will come swirling out of the nest taking to the air and so will many males. These ‘flying ants’ (properly called alates) are a wonder to watch on a warm evening, turning up on fly screens, window sills, around lights, in swimming pools., When all goes well, a male and female grasp each other mid-air, bite off each other’s wings and where they tumble down to the earth is where the new nest will be built. The wings flutter away in the wind.
I like ants and I hate ant poison. These are energetic and helpful rubbish cleaners around my garden. They eat all kinds of things including other insects but get their name from their love of sugar – they harvest honeydew from aphids and other sap-suckers – all part of the marvelous web of life.
I hope you appreciate ants, their amazing colonial lives, selfless work, role differentiation and adaptability. You might even like to give them a hand.
Focus On Fauna 