When it's a long-legged fly or dolichopodid, perhaps. Forget those pesky houseflies that buzz around our dining tables. They thrive largely thanks to the garbage that we so thoughtless leave out in the open, festering under the tropical sun into an irresistable nursery for grubby maggots. And sidestep the thought of vectoric mosquitoes, whose larvae wriggle in man-made puddles and swarm in stagnant pools at construction sites a world away from the fresh and flowing streams of friendlier forests.
Be glad that these parts lack the nasty creatures that plague other equatorial regions. In Africa, tsetse flies transmit Trypanosome protozoans as they suck blood, spreading the eternal slumber of sleeping sickness. The neotropics, as Benito Tan recounted earlier this week at the Linnaean Tercenteneray, boast a less fatal but arguably grosser family, the botflies that lay their eggs in the nostrils and skin of mammalian hosts. The grubs borrow under the epidermis, causing painful lesions that have to be removed surgically (read this account of a poor sod with botfly maggots in his scrotum) unless one desires to observe the imago prying its way out of your balls into the glorious open. Now imagine you were a cricket facing a parasitic Tachinid fly.
The few species that plague mankind with disease and blight are but a minute drop in the world of two-winged flyers. The order Diptera, with 130 families and 122,000 known species, cover almost every conceivable ecological niche, from pollination and predation to decomposition and parasiticism. Probably no terrestrial (and many aquatic) plant species in the world is immune to attack from some member of Cecidomyiidae, the gall midges (5,000+ known species) whose feeding larvae cause prominent swellings in the stems and leaves of their host. Fungus gnats (Mycetophilidae) which number 3,300 strong, target mycorrhizal prey but in the Antipodes, insectivorous members of this family have become a tourist trade that draws gawking visitors into caves for the dubious pleasure of seeing glow-in-the-dark grubs (fireflies, though are not flies but beetles).
In toilets adjacent to forested areas, some small and fuzzy moth-like insects can often be seen on the walls. These are moth-flies (Psychodidae) which are related to the sand flies that bother beachcombers. Robber flies (Asilidae, with 5,000 species) compete with dragonflies for mastery of the airspace, capturing in mid-air flying prey that is stabbed and sucked dry. There are flies that look and behave like bees, mimic wasps, appear remarkably beetle-like, as well as resemble and suck blood like lice. One 250-strong family of wingless, spider-like flies, Nycteribiidae, specialises in the blood of bats. The largest flies of all, the mydas flies (Mydidae), mimic spider-hunting wasps and hoverflies, growing up to 6 cm long with larvae that hunt scarab beetle grubs. And the science of evo-devo and genetics (and more lately, climate change) would have been nigh impossible without the raising and razing of generations of Drosophila fruit flies and their grotesque array of hopeful monsters.
As befits their name, flies are consumate aerial artists. They may sound repulsive and warrant it, laying as they do live larvae onto wounds and body cavities, but flesh flies (Sarcophagidae) are being studied for their vision physiology and neurological processing that allows males to pursue mates at a human equivalent of Mach 1.2. The bee-like hoverflies (Syrphidae) are perhaps the most effortless fliers, darting, pausing and zipping at will in midair like precision drones whose aeronautical secrets defy the dreams of flight engineers.
So flee not from the fly, especially those winged jewels such as the Dolichopodids and Micropezids (the stilt-legged fly pictured on top) that find refuge only in the shade and humid embrace of our few remaining forests. Feeding on smaller insects or fruit, these sparkling flyers bear no ill to anyone and cling to existence by tiny streams and muddy shores untouched by the itchy hands of men. Dainty wings will do no good, however, against the determined wheels of progress that relentlessly roll on without heed to the life-sustaining role of ecosystems and the uncounted costs of their destruction. Where then will man fly to, when the earth is mined to madness and bled dry of its green and growing lungs?
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