Mount Stuart’s small wildlife

peacock
Welcoming committee

Castle Hill dominates the central Townsville skyline but Mount Stuart takes over that role from anywhere further up Ross River. From Mundingburra all the way up to Kelso and across the river to the university and the hospital, Mount Stuart looms large.

That doesn’t mean people visit it very often, of course, but a road leading off the Charters Towers road just beyond the city winds up to a lookout beneath the radio masts. When I drove up a couple of days ago I was welcomed by a resident peacock (perhaps the same one who met me five years ago) and, after taking in the magnificent views over Magnetic Island, the Palm group and coastline all the way to Hinchinbrook, I wandered around the loop track.

The summit is a difficult environment for plants and animals alike: very exposed, very dry, and with only a thin covering of soil where there is any soil at all. Vegetation is ‘open woodland’ with a decent covering of tussocky grass, but most of the trees are tiny. Ants seem to be the most abundant invertebrates but there were other insects to be found as well as the spiders which prey on them.

* P.S. The ant has been identified by my friendly local expert as Meranoplus sp.

Lower down the mountain

Conditions half-way down the mountain are not quite so arid and I found more creatures per square metre than on the summit.

Notes

  • The two kinds of paper wasps are the two commonest around Townsville. More about them here and here.
  • The Spiny Orb-weaver pictured, Gasteracantha fornicata, is usually seen less often than its black cousins, Gasteracantha sacerdotalis, but outnumbered them on this trip.
  • “St Andrew’s Cross spider” is a common name which is applied loosely to several similar species. Argiope keyserlingi is the best known, A. picta is encountered from time to time, and this one may be unknown to science – which is a little bit exciting.
  • Golden Orb-weavers (Nephila sp.) are usually very big and not so brightly coloured but I have seen others around 12-15mm, like this one, in Western Queensland – at Aramac and Porcupine Gorge, for instance.

Moulting

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!

Mantis nymph emerging from skin
Neomantis nymph emerging from a skin it has well and truly outgrown

Another kind of mantis

A month ago I wrote about finding a group of tiny just-emerged mantis nymphs. (‘Nymphs’ covers all stages of development except adults, from just-hatched to nearly fully developed.) In a footnote to that post I mentioned a larger nymph I discovered a little later. I have been observing and photographing that one and its relations (at least two more hatchings, all on a particular patch of weeds) since then and now have a reasonably complete record of their development.

First, the hatchlings (click on any photo for a larger image). They are quite different from the ones in my previous post. Most obviously, they are paler and have pairs of brown spots all the way along head and body. Also, their head is much broader than their thorax, and their typical posture is different: straddle-legged and straight-backed.

Neomantis nymph
Spotty nymph

Mantises moult to move on to the next stage – the next ‘instar’ – of their development. The next stage I recognise is still completely wingless but the brown spots have faded. One or two instars later, wing buds appear; they have a faint mottling of darker green, as do the front legs. The nymphs are still straddle-legged but a new characteristic posture appears: they flatten themselves against the leaf they are on. They spend more time underneath their leaf than on top of it, at least by day.

Neomantis nymph older
Older nymph
Neomantis nymph
Nymph with wing buds 1
Neomantis nymph
Nymph with wing buds 2

 


Finally, the adult, about 20 mm long: the broad wings are translucent (note the leaf veins visible through them) and marked in a pattern of dark and light veining which resembles the pattern of the leaf itself. Around the ‘shoulder’ of each upper wing is a short row of yellowish spots, with minute black dots between them.

Neomantis adult
Adult 1
Neomantis adult
Adult 2


So what is it? Certainly a mantis (Mantodea, Mantidae) but not the common  green Garden Mantid (Orthodera ministralis). It looks much more like the mantid shown here as Neomantis australis, but that one is still different in several ways: it has narrower wings, is more nearly transparent and yellower overall, and has dark eyes (which may be due to the fact that it is a photo of a dead insect). CSIRO’s (poor) photo of Neomantis australis shows an insect more like mine but with a transverse pale stripe across its wings, more like the one I saw on Hervey’s Range.

I suspect there are at least two species or sub-species amongst all these but for now I will just call my little family Neomantis australis with one or two question marks.

Just out: praying mantises

We’re still waiting for rain but the warmth and humidity seem to be encouraging some insects to emerge anyway. I wrote about cicadas a few days ago, and on Sunday I spotted first one, then a dozen, tiny praying mantises on the railing of our back stairs. Here’s one:

very young praying mantis
Giving thanks for a safe emergence?

The picture is much larger than the mantis, which was only 8 – 10 mm long.

Figuring that there had to be a good reason for a group of infants to be together like that, I looked around and found their egg-case (ootheca) glued beneath the railing:

The egg-case or ootheca, with the popped cell-lids dangling from it
The ootheca, with the popped cell-lids dangling from it.

P.S. Here is an older nymph – more than twice the size – a fortnight later. I’m pretty sure it’s not one of these babies grown up, though, because it was too far away.

P.P.S. (Dec 28): The nymph I linked to now seems certain (as I have observed its development) to have been a different species of mantis from the one pictured above.