We took advantage of the Boxing Day holiday to drive down to the camping and picnic area at Alligator Creek. It is normally a popular spot but the long dry spell which only ended on Christmas Eve seems to have discouraged the campers and even the day-tripper numbers were down, so it was pleasantly quiet. We paddled in the shallows, swam in the deeper pools, clambered over the rocks and enjoyed a picnic lunch. All of us are enthusiastic about wildlife and all of us had cameras so my photographic haul for the day is only about a quarter of the total.
We all took photos of the scrub turkeys, Alectura lathami. There were plenty of them around and they were absolutely comfortable with human society – even to the point of shopping at Supré, apparently:
They are large and somewhat clumsy birds but my third photo here is misleading: the bird did not crash-land at all but was enjoying an energetic dust-bath. A far more formal portrait is here, on my Flickr photostream.
The scrub turkeys were not the first creatures we noticed on arrival: the cicadas were. Their screaming drone is characteristic of the Australian bush in summer and dominated the picnic area. After a while we saw some of their cast-off shells (here and adjacent) clinging to tree-trunks and saplings but we never did see any of the adult insects; they must have been high in the trees.
I also brought home pictures of spiders – another ant-mimicking jumping spider, a tiny yellow spider which had somehow defeated a green-ant plus a couple of others – flies (1, 2), dragonflies, damselflies and a marvellously camouflaged mantis:
A post about an earlier visit to the same park shows the scenery and some more of the fauna, while this link will take you to a composite collection of my Flickr photos of the wildlife.
Insects and spiders can’t grow steadily like we do because their skeletons are on the outside and serve simultaneously as skin, skeleton and armour. It doesn’t grow or stretch once it has hardened so the animal has to grow a new skin underneath the old one, crack the old one open and crawl out, and wait nervously until the new one toughens. I have seen different parts of the process in different insects recently so I thought I would put a group together.
Dragonflies: Juvenile dragonflies are so different from the adult it is hard to believe they are even related. They are water-dwelling predators which fishermen know as ‘mud-eyes’ and use as bait. After several moults in this form they climb up out of the water and split open to emerge as the winged adult dragonflies we know and love. I have yet to see it happen but here is a lovely photo from SE Qld.
Cicadas: Cicadas also undergo a radical change, since the nymphs live underground, emerging as stumpy-looking bugs with strong burrowing front legs and splitting open to emerge as a winged adult. I haven’t seen one emerging but here is a cast-off skin (known as an ‘exuvia‘), and here and here are some adults
Cockroaches: We have a resident population in our compost bin and I caught this photo recently of a just-moulted cocky resting next to its old skin. Like many (perhaps most) insects, fresh-moulted cockroaches are nearly colourless as well as soft; they darken as they harden.
Mantises: I found this cast-off skin eighteen months ago but I didn’t see one in the process of emerging until yesterday. It is one of the family I have been watching recently and described here. In terms of that post, this is a nymph with wing-buds emerging from one without. One photo of it is here and another is below.
In all cases, the amount of change from one stage (‘instar’) to the next is hard to believe. Even when they don’t change from swimmers or diggers to fliers, the difference in size makes you wonder how on earth that big bug fitted inside that little skin.
In human terms the changes would be (roughly) like changing from a one-year-old to a three-year-old overnight, then to a six-year-old, to an eleven-year-old and finally to an eighteen-year-old. What a difference that would make to our lives!
If you read my title carefully you probably thought I had made a mistake but no, it was deliberate – an attempt to capture this effect:
I mentioned recently that our cicada season has started. We don’t have very many in our own garden but I visited a neglected garden on Hervey’s Range yesterday and was surprised to find the ground beneath one particular tree looked as wet as though a sprinkler had been on (and I knew it hadn’t). Looking up, I saw and felt a steady shower misting down from above, and spotted the cicadas responsible. Here’s a closer view:
There were hundreds, if not thousands, on this one tree (hardly any on nearby trees of different species), all sucking the sap for its nutrition and excreting the watery waste. If this goes on too long, the tree may not survive.
A ‘collective noun’ is the name for a group of animals – a ‘flock’ of sheep, etc. It seems that there isn’t one for cicadas, and I doubt that ‘superfluidity’ will catch on. We need one which highlights the most obvious characteristic of a big group, and that is surely the noise. I thought of a ‘clamour’ but that is already taken, by rooks. Other people (I looked on the net) have suggested a ‘chirrup’ or a ‘twitter’ but those are far too weak, too genteel, so I will propose a ‘scream’ or a ‘shrill’ of cicadas. This lot earned both of them, as well as a ‘superfluity’ and ‘fluidity’.
Our first cicada for months – perhaps since January – flew in through an open window last night. They seem to start appearing around the end of October each year, nymphs digging their way up out of the ground to climb up any convenient plant stem or trunk and split open to emerge as winged adults like this one. Here is the adult of another species from last year.
They look like they ought to be classified with grasshoppers and katydids, in Orthoptera, but in fact they are grouped with shield bugs and the like in Hemiptera. Why? Because they suck sap rather than chewing leaves. Wikipedia has a good general article about them if you want to know more.
Update, 21 November: I found the cast-off shell (exuvia) of a cicada nymph hanging beneath a pentas leaf. It is probably not the shell of the cicada above and may not even be the same species, but it must be similar and you can see it here on Flickr. Note the split down the middle of the back which the adult insect emerged from.