What’s around – mid August 2012

mating craneflies
A mating pair of Tiger Craneflies, Nephrotoma australasiae. Legs everywhere!
The sexes are very similar but the female (at top of this picture) is more heavily built.

The total rainfall since my previous mid-month summary is exactly zero, and the relative humidity has been very low, too: below 20% at 3pm every day for the last two weeks, for instance. Temperatures have consistently swung between 8 – 10C overnight and the mid twenties during the day. Cool and dry is not what the bugs like and I’m beginning to think of them as being in ‘maintenance mode’, just ticking over and waiting for some warmth and moisture.

The paperbark is flowering, as I mentioned a few days ago, and so is the mango tree. The Macadamia is almost ready to follow suit, and so is the Poplar Gum. Each of these trees attracts its own group of nectar-feeders. The birds love the paperbark (as I mentioned in my previous post) and the poplar gum, but are not particularly fond of the other two. The honey bees don’t seem to care for the mango blossom but love the other three, so that pretty much leaves the mango to the butterflies, the flies (mainly hoverflies), wasps and native bees.

large hoverfly on mango blossom
Hoverfly on mango blossom

I’m seeing …

    • Quite a lot of little orb-weaving spiders – Silver Orb-weavers (Leucauge granulata), Spiny Orb-weavers ( which I now believe to be Gasteracantha sacerdotalis rather than Austracantha) and St Andrew’s Cross spiders; also quite a lot of jumping spiders (Salticidae), some Lynx, and a few flower spiders.
    • Hoppers and their nymphs, which often become food for the above.
    • Butterflies: reasonable numbers of Junonia and Eurema and grass moths; very small numbers of everything else but including Migrants, Skippers, Melanitis leda and recently one visiting Orchard Swallowtail.
Giant grasshopper on variegated leaves
Giant grasshopper on giant variegated lily
  • Diptera (Flies): Long-legged flies (see bottom of this page), Hoverflies (see at left) and Blowflies, with occasional soldier flies and craneflies (above) and – still – mosquitoes.
  • Hymenoptera (wasps, bees and ants): occasional little wasps including paper wasps (though no nests that I’m aware of) and a very few mud-daubers; some native bees again recently after a gap of a few months; the usual small ants and a slowly-growing green-ant colony.
  • Others: a few Giant Grasshoppers; a healthy population of cockroaches in the compost bin; but no mantises (although saying that usually ensures I will see one in the next day or so).

Same time a year ago

Microfauna (3) flies

When I started taking a real interest in invertebrates, flies were the group that surprised me most. Time after time, something I thought was a wasp or bee, even a dragonfly, turned out to be a fly. As the Queensland Museum says,

Flies belong to the Order Diptera. In Australia there are almost 7500 described species in 100 families. … Many sorts of insects are called flies but “true flies” are a distinct group of insects which have only one pair of wings, unlike the caddisflies, scorpion flies, mayflies and butterflies that have two pairs of wings. … True Flies are found everywhere, and include delicate craneflies, mosquitoes, and midges, as well as robust horseflieshouse flies and blowflies. …

If the stereotypical response to spiders is “Eeek!”, the response to flies is “Yuck!” Both responses are unfair, if only because of the enormous diversity of these families: many, probably most, of them are not at all scary and not at all disgusting in their habits. The QM again:

Biting, blood-feeding flies such as mosquitoes, midges, horseflies and blowflies are able to transmit diseases to humans and domestic animals. … But most flies are not pests, most are important decomposers of plant and animal matter.

This page doesn’t include any of the Diptera that we don’t usually think of as flies, e.g. mosquitoes and midges. None of them are as big as a house fly, which is 5 – 8 mm long, and most of them, like most of my tiny spiders and miscellaneous other tiny insects posted recently, are 2 – 5mm.  I don’t know much about some of the species pictured here, because they are so small they have escaped even my notice until recently, but I will give what information I can.

fat red fly with barred wings
Signal fly, Platystomatidae, Rivellia sp., about 4mm long.
slim brown fly with long legs
About 6-7mm long but very slim, probably a crane fly, Tipulidae. Resting on a Dianella lily.

Crane flies often don’t feed at all as adults, living only to breed. When they do feed, they feed on nectar. Bigger relations of this little one are very common, and here is a picture of one sipping from mango blossom.

Squat black fly with red eyes
Only about 2mm long but built like the proverbial Mack truck. Why? I don’t know. What is it? Ditto.
Colourful fly
2-3 mm long and strikingly coloured, and that’s about all I know.
metallic green fly with black-banded wings and abdomen
A Long-legged fly, Dolichopodidae, probably Austrosciapus connexus, about 4mm long.

The Long-legged flies are tiny counterparts to dragonflies in that they are swift, agile aerial predators. They are common in my garden year round but are very difficult to photograph because they are so fast – they usually jump at the beginning of the flash and show up as a blur on the edge of the picture. Dragonflies are not true flies, of course (they have four wings). One small indication of the diversity of our flies is that there are almost as many Australian species of this one family (about 320) as there are of all Australian dragonflies.

Most Dolichopodidae that I see are metallic green or gold, but some are less showy:

Long-legged grey fly
Dolichopodidae again, a little larger than the one above.

More about flies: CSIRO entomologyWikipedia/FlySOWN/Diptera.

Horned flies

When we think of horned males fighting over females most of us will think first of deer. All those dramatic photos of rutting deer with locked antlers have to have their effect, I suppose, but it’s a bit bizarre that are we are so conscious of exotic wildlife and forget our own.

Of course, our own horned battlers are a bit smaller – not crocodiles or kangaroos, not even koalas or quolls, but insects. I wrote about the Rhinoceros Beetle a month ago. They are quite big enough to impress onlookers. Then I came across something much smaller still and completely unexpected, a tiny fly with the same equipment which it uses for the same purpose. Meet Wawu queenslandensis:

Horned fly, Wawu queenslandensis
Horned fly, Wawu queenslandensis

He’s smaller than an ordinary domestic fly but he is colourful and well-armed, and fights for females just as Rhino beetles and deer do. He has a cousin, slightly smaller but even more fearsomely (to other flies) equipped; a photo of a dead specimen is here and the pin will give you an idea of just how small he is. Females, by the way, are hornless, as they are in Rhino beetles and most deer.

It makes one wonder just how far back in the evolutionary line some kinds of behaviours really go. Do deer do it because their ancestors all the way back to the common ancestor of deer and flies, hundreds of millions of years ago, have done it? Or has it evolved separately several times, as some other features have?

What’s around – mid February

Green Katydid
Katydids have much longer antennae than grasshoppers. This nymph's antennae are about twice its body length.

Our Wet has been pretty half-hearted so far. We have had showers and storms but nothing like the widespread soaking rain that we expect.

If I had to summarise what’s happening now in our little world of insects, the key word would be ‘green.’ There has been enough rain to encourage all the plants to grow, and the plant-eaters – especially grasshoppers and hawkmoth caterpillars – are taking advantage of the abundant food. Not only that, most of them want to stay camouflaged and so they are as green as what they eat.

More systematically:

  • Grasshoppers: lots of young ones, plus some young Katydids (mentioned here because Orthoptera covers Grasshoppers, Crickets and Katydids).
  • Butterflies: Pale Triangles (some yellow form now as well as the blue variety); Common Eggfly and Blue-banded Eggfly, but all of them males; Migrants and Crows; passing Ulysses, always special; occasional Orchard Swallowtails and what looks like a caterpillar; a fair number of Hesperidae; still no Eurema or Junonia.
  • Moths: Lots of little grass moths; a few adult hawk moth sightings, and lots of their caterpillars munching their way through our Pentas.
  • Mantis: still a few Neomantis nymphs on the weed I found them on, but they seem to leave home as soon as they can fly.
  • Dragonflies: a few in the garden, lots more closer to permanent water.
  • Flies: lots of red-eyed blue blowflies (Calliphoridae), some Soldier Flies, Stilt Flies and little, long-legged, green flies (Dolichopodidae) but hardly any Hover-flies (Syrphidae). Mosquitoes are Diptera (flies) too, and they are making up for the shortfall in the numbers of their relatives.
  • Wasps and bees: a few active mud-daubers and paper wasps; not as many Ichneumonidae as there were a month ago; a few Resin bees and Blue-banded Amegilla bees.
  • Spiders: some Lynx and Jumping Spiders, and quite a lot of Silver Orb-weavers. A few adult St Andrew’s Cross spiders, and a lot more to come because I have seen hatchlings. Still no little spiky Austracantha; and still no big Golden Orb-weavers  although last year we had them from December through to June.
Jumping spider and grasshopper
This grasshopper was not well enough camouflaged and not quick enough, and the Jumping Spider got him.

Orchid – fly – spider

Spray of purple orchids
The flowers

While we’re on spiders, and particularly flower spiders, here’s another – in a setting which neatly demonstrates cause and effect in the food chain.

Our golden orchids flowered a few weeks ago and a purple one followed suit last week. The golden orchids are almost scentless (as far as I’m concerned, anyway) but the purple ones have a strong, sweet perfume which obviously attracts our (in)famous Queensland Fruit Fly, Bactrocera tryoni. There were always a dozen or more of these on the orchid spray, and they came to it last year as well although I don’t usually see them around the garden at all.

A careful look at the orchids revealed another kind of creature on them – flower spiders, there for the fruit flies. The brown one pictured was the bigger of two that I found; the other was the same species as the Flower Spider which caught the wasp, but a smaller individual. Both belong to the same family, Thomisidae, commonly known as ‘Flower Spiders’ and, perhaps mystifyingly, as ‘Crab Spiders’ but I haven’t got a more specific identity for the brown one yet.

Queensland fruit fly on orchid
The fly
Brown and white spider on orchid
The spider
Spider and fly on orchid
Relative sizes

Here’s the Thomisidae family description from Ron Atkinson’s Find-a-spider Guide, which incidentally explains the origin of the common names:

The body is small to moderate in size. The abdomen is somewhat large and more variable in shape than the cephalothorax. The legs are visibly spiny, especially the first two pairs which are very robust and curve forwards in crab-like fashion. The body colour may be white, green or brown to match the colour of the surfaces on which the spider is most likely to be found. The usual habitats are on leaves, in flowers or on/under bark. In the last of these habitats the spider’s surfaces are roughened to improve the camouflage.