Flies: More than meets the eye

The humble fly (Photo by Christina Renowden)

“Look deep into nature, and then you will understand everything better” (Albert Einstein) 

It’s a warm summers day, the BBQ is sizzling, the salads look scrumptious, you’re relaxed sipping on a bevvy watching your mate fry up a feast.  Then like clockwork, they arrive, the pesky flies buzz around your head land on your food and proceed to poop and vomit all over it.  Great.  But, is this all flies do, did they evolve with one purpose, to annoy us?  What use are flies to the world?

These questions matter as we continue to lose biodiversity at an alarming rate and it makes me consider the value we place on animals that annoy us, or we find vulgar and unattractive. In the wise words of ecologist E.O. Wilson, he argues

that every scrap of biological diversity is priceless, to be learned and cherished, and never to be surrendered without a struggle.

So how do we accept and even appreciate the humble, often disgusting, fly? Perhaps by digging a little deeper into the life of flies we learn these little insects do us more good than harm.

The good, the bad and the ugly of flies

Let’s start with the harm. Flies are well known for their spread of germs as they feed on decomposing animal and plant matter then prance all over our food potentially transmitting pathogens that can make us sick.  Flies aren’t equipped with teeth or a munching jaw, so they spit on their food helping them dissolve it for easy eating. You say yuck, I say fascinating (note to self however, definitely don’t leave food around to be pooped and spat on by flies).

But with every dark cloud there is a silver lining, right? Absolutely. Some flies are leading the way in cancer research while others are protecting our food crops. Yes, the pesky house fly is a nuisance and can transmit germs.  However, there are many hundreds of species of fly in Australia doing remarkable jobs, some of which are of great benefit to us.

Cue the not so hideous ‘flower flies’

A case in point, is the hoverfly. I am quietly obsessed with these little, two-winged insects mimicking bees and flying like a helicopter, what little legends. In an amazing evolutionary phenomenon, hoverflies have taken on the black and yellow patterning we tend to see on the European Honeybee.  A very neat trick to keep potential predators at bay.

Just as helicopters manoeuvre forwards and backwards so does the hoverfly, seeking out flowers through visual cues and their sense of smell.

Affectionately known as ‘flower flies’, hoverflies are part of the Syrphidae family in the Order Diptera (two-winged insects). (Photo by Christina Renowden)

Hoverflies work hard for a living

Hoverflies eat nectar and pollen just as butterflies and bees do.  In doing so, they are important pollinators and perform a critical role in ecological communities spreading pollen between flowers enabling our native plants (and food plants) to replicate and flourish particularly when there are fewer bees around.

For the gardeners out there, you will know the dreaded plant-sucking destruction of the aphid.  A small green bug that can wreak havoc in gardens and agricultural crops.  As it happens, hoverflies really shine when they are in their larval stage (#maggots).  As they are voracious and important aphid predators, they even have a special name for this: ‘aphidophagous’; try saying that ten times.  A very handy and safe form of organic pest control.

Telling the difference between hoverflies (top) and European Honeybee (bottom): look for a single pair of wings on the hoverfly (two pairs for bees) short antenna (long on bees) and characteristic ‘flylike’ compound eyes – think Bono in sunnies. (Photos by Christina Renowden)

So next time you swipe at a fly, don’t put them all in the disgusting basket.  Perhaps shift your perspective and spare a thought for the diversity of flies and their unique ecological roles in pollinating native plants and keeping our gardens and food crops and healthy.

Further reading:

Rodríguez-Gasol, N., Alins, G., Veronesi, E., & Wratten, S. (2020). The ecology of predatory hoverflies as ecosystem-service providers in agricultural systems. Biological Control, 104405.

8 Responses to “Flies: More than meets the eye”

  1. Thanks Sidney, yes other flies can be a real interesting lot!

  2. Sidney Ruthven says:

    I study genetics so spend a lot of time with drosophila melanogaster but it is really cool to think about the other flies out their.

  3. Thanks Madeleine, I am glad you liked it 🙂

  4. Thanks Bingkun for your comment. Well perhaps we could say one of the good traits of house flies is they eat rotting meat, fruit and vegetables so in some ways they are are nature’s cleaners… but the problem is when they then walk or land on our food after their feet have been dancing around on dead animals or rotting food! The other ‘good’ trait about house flies is they would be an important food source for other animals – such as spiders, praying mantis, frogs and lizards…

  5. Thanks Mon, I am glad I have changed your perspective on flies 🙂
    So Hoverflies as adults eat nectar and pollen, however their larvae (maggots/grubs/babies) eat a whole range of things, but one of their favourites is aphids. I hope that clarifies 🙂

  6. Bingkun Du says:

    I never really considered whether flies could be of any help other than pester us and our food, let alone be used for cancer research. It is quite impressive they have more functions. Just clarifying, does it mean house flies don’t have any ‘good’ traits like the hover fly?

  7. Madeleine Hedin says:

    Hi Christina, what a fantastic topic to highlight as we welcome the new season, and all the flies along with it! The rate of biodiversity loss on this planet is truly terrifying, and it certainly calls for a huge shift in our relationship with bugs, a relationship which I think is so fascinating! It is great to see someone celebrating flies in this way, and I hope it helps others to better understand and appreciate their significance.

  8. Mon says:

    Hi Christina! I really like the introductory paragraph. I could just close my eyes and imagine the scenario that you have written for the blog post.

    You also changed my perspective of flies. Before I read your post, I thought flies are just a nuisance and Ewwww! I didn’t know flies are so useful to us (be it cancer research or keeping our crops healthy) until I read your article. (:

    Just like to clarify. So, hoverflies eat aphid, nectar, and pollen?

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