Walking the beach, minding my own business, recently showered and feeling suave in a newly washed shirt [if the term ‘suave’ could ever be applied to me] … I was suddenly besieged, set upon, festooned! They arrived in numbers incalculable – an unprovoked air-to-surface ‘Blitzkrieg’ from Musca vetustissima, the Australian bush fly.
I didn’t need an elaborate set of mirrors to tell me that I had a ‘Fly-Central’ landing strip between my amply-padded shoulder blades. Seeing the dapper man but a few dozen paces ahead disappear under a similar attack, his white shirt polka-dotted to near-black by a like swarm, was sufficient to picture my own fate.
Doing my best impression of Shuggie Bain, that heroic wee bairn from the 2020 Man Booker Prize winner of the same name, I muttered under my breath in my best Glaswegian accent … “is no’ right … no’ ‘ere by the sea” … then soldiered on into the mobile cloud that clearly was deserting the slim pickings on the shoulders of ‘Mr Dapper’ ahead in exchange for my more-promising ground zero.
Laughing aloud in the face of my Aerogard stick, they landed, then – I presumed – vomited! I promised myself that if ever I made it home, I would try to find out a little more about this ubiquitous ‘child’ of our Australian summer skies. And, yes, this troublesome wee critter is a unique Australian, as it is found nowhere else.
First, and to be fair to Musca vetustissima, there are worse insects – for though the bush fly tickles and has an annoying preference for our eyes, nostrils, and mouths, they don’t bite! They are not a Scottish midgie [the worst], or a Milford Sound sandfly [a distant runner-up] … so perhaps we should be grateful for small mercies.
Furthermore, it seems that – unlike the common house fly [the Blow fly*] that does vomit on us as it lands, or the slow, invitingly swattable March fly* that does bite – the wee vestustissima neither pukes nor bites. It dances!
*NB: Blow flies that buzz [Family: Calliphoridae] and March flies that bite [Family: Tabanidea] belong to quite separate insect families. Blow flies are found all over the world, as are March flies [except for Greenland, Iceland, Hawaii, and the poles]. March flies – known as ‘horse flies in the US and UK – are common in Lorne and bite … though it is ONLY the female of the species that does!
After that brief aside, back now to our proud and unique little Australian, M. vestustissima! Dr Maggie Hardy of the University of Queensland, who has leapt bravely to the defence of the little bush fly, maintains it ‘has got a bad rap’. Paraphrasing a description by Genelle Weule of Maggie’s work [Ref: 1], it turns out that our bush flies “… explore their world by using their feet – feet that are uniquely designed to cover the greatest possible surface area.” Furthermore, says Hardy: “It is not really a pest” … NB: that’s a matter of opinion … “it does not spread disease, it does not hurt our livestock or agriculture, and it likely helps pollination.” And – importantly – it is a vital link in the food chain, both as a hunter and the hunted.
Their tiny tootsies ”… can stick to just about anything. They have special adhesive pads containing small hairs that produce a type of glue made out of sugars and oils.” Indeed, I have often marvelled at how flies [and other insects and spiders] manage to adhere, upside down, to an otherwise flat and smooth surface without plunging headlong to their death – as would we. This is the likely answer.
https://fineartamerica.com/featured/cluster-fly-foot-sem-power-and-syred.html
Think on this: it turns out that as these mini-sized ‘Great Australians’ walk on us, their feet are actually ‘smelling us’. Weule’s article continues: “… the sensory receptors in the hairs on their feet can ‘smell’ things like pheromones from us and/or from other flies. Furthermore, they are very sensitive to changes in direction or humidity and can actually ‘smell’ or ‘detect’ carbon dioxide [CO2].”
In this last respect, they are very much like mosquitos. Mozzies are also attracted to CO2 – indeed this is thought to be how we seem to attract them to us when we sleep at night.
They literally zero in on us as we breathe out our CO2 like a ‘call signal’.
Events – for example: the Mountain to Surf – offer the bush fly a slice of fly heaven! As they are attracted by tears, saliva, and sweat, and they just love a warm summer day. Some weeping after recording a poor time [tears], while
slobbering down a power-drink [saliva], in a proper hot lather at the finishing line [sweat], is a gourmet ‘trifecta’ for a vetustissima!
Ha, then … just swat them away! … No such luck! They evade a swat as easily as my racquet would [somehow] manage to evade returning a Rafa serve.
Not only do bush flies have remarkably well-designed wings: two sets, one large, one small, that provide both amazing balance and a turning circle unparalleled by anything humans have yet built … but their vision is extraordinary, too.
https://news.stanford.edu/2017/08/31/new-solar-cell-inspired-insect-eyes/
They sense our flailing hand by using complex compound eyes that are a whizz at detecting changes in light and shade. In addition, their wings can detect the subtle changes in air pressure that precede our advancing palm. They can ‘see’ our hand moving almost before it moves!
We might think that we are being as fast as a speeding locomotive, but they are way ahead of us, just from detecting the sudden changes in light and barometrics.
Noted Maggie Hardy: “… flies are the best of all the animals that we have studied at seeing something move”.
So, as ‘Mr. Dapper’ returns to his car – and donates his fly forest to the only remaining solitary back on the beach– I resign myself to the inevitable patter of a myriad tiny ‘sniffing’ feet as they stamp and dance their summer jig across the landing field of my shoulders.