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 horseflies, house 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.
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.
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: