There isn’t much insect activity in the garden at this (dry, cool) time of year but when I was ambling around it last week I saw a Green Ant which was too small – only about two thirds of the size of a normal Green Ant.
That was my first thought, anyway, but a closer look revealed that it wasn’t an ant at all but a very good mimic. It is a juvenile Pod-Sucking Bug (Riptortus sp., Alydidae, Hemiptera) and in fact is the same species I described here on Green Path four years ago. That post shows older juveniles, gradually less and less like the Green Ant; this very small one turns out to be the best mimic of all, other than being too small.
This second image clearly shows its proboscis or sucking tube, tucked away beneath its body until needed.
Townsville is still waiting for the rain – all we’ve had is a 12mm teaser nearly a week ago – but the garden is coming to life anyway. I spotted this mating pair of shield bugs (aka stink bugs, Poecilometis sp., Hemiptera, Pentatomidae) a few days ago, and they are not alone. Hawk moth caterpillars are stripping our pentas plants and madonna lilies (I wonder why they like those two in particular?) and we often see courting pairs of Cairns Birdwing butterflies. Other butterfly numbers are building up, too, especially the Pale Triangle and the Clearwing Swallowtail.
A week ago I mentioned my surprise and disappointment at how few bugs I found in a Hobart garden in the week after Easter. One of the expert Tasmanian bug-hunters I mentioned in that post was amused by my reaction:
I had a good laugh at your disappointment … Unfortunately you did come down at the beginning of the ‘slow’ period (especially bad April to August). We do have winter insects but for the most part it’s more a specialist pursuit of the very small critters :-)
In retrospect, I think there were two reasons that the low numbers surprised me. One is that my memories of childhood in South Gippsland (the nearest thing to a Tasmanian climate I have experienced) have probably been skewed by the fact we didn’t spend much time outdoors in winter, as well as blurred by the decades in between. The other is that I hadn’t really thought about the difference between Tasmania’s seasonal variation and Townsville’s. We have comparatively little variation in day length or temperatures and our far greater variation in rainfall seems not to matter quite so much. (N.B. the temperature scales on these two charts are the same but the rainfall scales are not.)
A stop on the way home from Reef HQ Aquarium on Thursday drove home the difference quite emphatically, although quite by accident. I pulled up beside a mangrove creek which runs through a narrow strip of parkland between South Townsville and Hermit Park (something I have done several times before – see this post and links from it) and in the space of half an hour or so I was able to photograph, not just observe, more species of butterflies and more species of true bugs (Hemiptera) and more species of spiders than I had seen in my entire week in that South Hobart garden. I also saw, but didn’t photograph, another species of butterfly, some small grass moths, two species of native bee and various flies.
Other insects: a female Shield bug (Poecilometis sp.) sheltering her nymphs under her body, a tri-horned Hopper, Assassin Bugs, flies, grass moths, Blue-banded bee, another bee or wasp which may have been a Fire-tailed Resin bee, two species of paper wasp (Polistes stigma and Ropalidia romandi) and at least two species of ant
Spiders: a very young St Andrew’s Cross spider in its web, and three species of jumping spiders – Cytaea plumbeiventris and two I haven’t identified yet.
The links on this list mostly lead you to older photos, here on Green Path or on my Flickr photostream, but a couple taken on the day deserve more attention. One, showing the kind of behaviour that makes the observer rethink butterflies’ sweetness-and-light reputation, is featured at the top of this page.
Assassin bugs (Reduviidae) are common enough but this was the first time I had seen new hatchlings (here is a bigger one in the same parkland). They were dispersing down the mangrove twig away from the cluster of eggs they had just emerged from.
I am not actually an ant at all, but looking like one may save me from critters willing to eat harmless vegetarian bugs like me but unwilling to attack nasty-tasting, big-jawed ants.
Starting again, a bit more seriously: these photos show a couple of insects I found together in my garden recently. The first is about 6mm long, the second about 8mm. My first and only thought was that they were ants, although the transparent rim around their bodies looked strange for an ant (and just as strange for anything else) and so did the bracket-shaped shoulder-piece of the larger one.
I uploaded both photos to my Flickr photostream and the good people from the Field Guide to Australian Insects and Encyclopedia of Life Images soon put me on the right track: “I’m guessing that these are close to the Broad-headed Bugs (Alydidae). Both seem to be immature stages and the wings have yet to develop completely. The adult would have wings covering the abdomen,” and, “not an ant but an Hemipteran nymph … it vaguely resembles other ant-mimic bugs in the family Nabidae I know from Europe,” and, “Definitely an ant-mimicing heteropteran nymph. We (Aussies) have numerous species spread among several families that have ant mimics as nymphs,” and, “Semi-transparent seams give the impression of several constrictions, where there are none!” (Clicking on the images on this page with take you to Flickr, where you can see the whole discussion as well as full-size photos.)
In this light, the puzzling features weren’t so odd: I know a native cockroach and a beetle which have transparent edges to their coloured carapaces, and the ‘shoulder-piece’ is simply a pair of wing-buds.
Once the right track, I succeeded with an image search. The best match I found was on Brisbane Insects’ invaluable site, Rhyparochromidae – Seed Bugs, which told me that Rhyparochromidae is a family closely related to Lygaeidae (Seed Bugs, Milkweed Bugs and Chinch Bugs). They are small dull brown or blackish bugs which eat seeds; many of them are flightless. When (if) my bugs become adults, they should look something like this or this (not my photos), with wing patterns mimicking the ant-like body segmentation.
These bugs are far better ant-mimics than the jumping spiders I found a while ago. Some of their relations are pretty good, too – visit Brisbane Insects’ ant-mimicry page to see them.
When we are photographing small insects, the available light is crucial: we need a small aperture for the depth of field, which means a long exposure time (in which the bug might move) or a lot of light. We therefore use flash quite often.
The effect is frequently unnatural, since the flash illuminates the subject without reaching the background, but can be attractive. This shot is typical: the little sap-sucker was hanging around in a shady part of the Palmetum late in the afternoon – not the middle of the night as one might think – and the vegetation behind it has vanished into stygian gloom.
The Palmetum is one ‘campus’ of Townsville’s botanic gardens. Its special focus is palm trees, as its name implies, but palms range across so many habitats, from rainforest to desert, that the gardens are very varied. I found lots of wildlife to photograph on a Saturday afternoon stroll, even well into the Dry season.
There were plenty of birds – Rainbow Lorikeets, Ibis, Black Duck and a few other familiar species, plus one which I had to look up. My first thought that it was a honeyeater, since it was about the size of our Blue-faced Honeyeaters and had a similar patch of bare skin on its face, but it turned out to be a Little Friarbird. I hadn’t been far wrong, however, since friarbirds are members of the same family (Meliphagidae) as honeyeaters.
But insects claimed most of my attention, although numbers were down in the park just as they are at home. I found a peculiarly-equipped bug, several species of orb-weaving spiders, damselflies around the lagoon and in the rainforest, a few dragonflies and a few butterflies.
These butterflies are seen year-round but their colours, like those of other leaf-mimics, depend on the season. Melanitis leda, the Evening Brown, is my favourite example of how they change – look at this collection.
This picture could well have appeared in my gallery of microfauna a few days ago but I thought it deserved a little more prominence.
What do we have? Two insects on a plant stem, obviously. Two completely unrelated insects, most of us would think – like a man and his dog leaning against opposite sides of a lamp-post, for instance – but we would be wrong: they are the same species. The one on the right is a juvenile – a nymph – of the larger winged insect on the left.
They are Hemiptera – ‘true bugs’. The adults are known as leaf-hoppers or plant-hoppers and these two are probably Colgar rufostigmatum or Colgaroides acuminata in the family Flatidae. The nymphs, as far as I can tell, are not known as anything at all. They are only about 5mm long without the peculiar tail of waxy filaments and are easily overlooked. The adults are more visible, at 8mm or so, but can easily be mistaken for a spine or new leaf on the stem of the plant. Like many Hemiptera, they feed exclusively on sap they suck from the plant.
Insects of many families undergo radical transformations during their life cycle, of course. The caterpillar-pupa-butterfly sequence is well known (but still amazing); cicadas spend their long childhood underground, eating roots, and dig their way out to split open and take wing; dragonflies spend their infancy as ugly aquatic predators before climbing out and emerging as adults; and so on. By comparison mammals (like us) are boring … just about all we do is get bigger.