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/Fly.

4 thoughts on “Microfauna (3) flies”

  1. Hello,
    I was wondering if you can tell me a little bit about the Black Squat Fly you have pictured above? I would really love more information as to where it is found. Thanks,

    1. Hi, Julie,
      All I know is that I found it in my (suburban Townsville) garden. They are not common there, however, even allowing for the fact that anything so small is easily overlooked.

Leave a Reply

This site uses Akismet to reduce spam. Learn how your comment data is processed.