It's a Small-headed Fly from South Africa! - Observation of the Week, 4/26/20

Our Observation of the Week is Psilodera fasciata small-headed fly, seen in South Africa by @cecileroux!

Cecile wrote a wonderful little piece for this week, so I’ve decided to publish it here in full. I’ve added some links to her text and appended a paragraph about this remarkable family of flies. Enjoy! - Tony

I was lucky to be born into a family that loves nature. I have always loved being immersed in nature, watching, listening, appreciating. My mother studied Entomology, but I only started following in her footsteps when my husband gifted me a camera with a macro lens. I was immediately hooked! 

Shortly after getting the camera, I was introduced to iNat by a botanist friend, @steve_cousins, who has since sadly passed away. He was doing his doctorate on our critically endangered Renosterveld, and while he studied the vegetation, I followed and started to record the infinite variety of insects and spiders in some of the few remaining veld remnants in the Swartland. We talked about pollination, and the importance of bees, and as I watched the flowers, I was amazed to see the variety of pollinators. I realised that not all that buzzes are bees, and started to look closely, and that is how I first came to know the small-headed fly, Psilodera fasciata. Along with the Bombyliidae family, they are some of my favourite flies, and I am grateful that they seem to like my rather unkempt indigenous garden, where I found this one. One needs patience to photograph these flies, they take ages to decide where to settle down. But the patience and sore knees and dirty elbows are always worth it!  Lockdown is made better by the company of all the insects and spiders in my garden.

Currently some friends and I are endeavouring to record the abundance of life on Kasteelberg, the mountain guarding over our village. The renosterveld and fynbos vegetation, the birds, small mammals, reptiles and invertebrates. I am at my happiest when I am out in the veld, discovering and observing. My main interest is spiders, but I am captivated by every small thing that moves! The best part of observing the small life around me, is being amazed and excited almost every day, a wonderful privilege in a jaded world. So much to discover still! Apart from my own pleasure, I also hope to teach people through my photos that insects are not pests, and spiders are not to be feared.

I am not a scientist, and field guides, although invaluable, can go only so far. I find iNaturalist a wonderful site where like-minded and knowledgeable people from all over the world become teachers. I am learning so much, and appreciate every ID and discussion.

Psilodera fasciata is a member of the Acroceridae family, known commonly as small-headed flies or spider flies, which contains about 500 species around the world. While the inspiration for “small-headed” is obvious from Cecile’s photo, “spider flies” refers to this family’s predilection for parasitizing our eight-legged friends. Female Acrocerids lay hundreds or even thousands of eggs. Hatchling larvae seek out spiders and make their way to the host’s insides, consuming it from within then pupating outside of the host’s depleted body. Adults feed on nectar and often possess enormous proboscises, as Cecile photographed here. When not in use, the fly tucks this proboscis under its body, and you can sometimes see it protruding past its rear end.

- Speaking of egg laying, check out an Acrocerid doing just that - in slow motion!

- Here’s one with an insanely long proboscis, photographed by bernardo_segura.

Posted by tiwane tiwane, April 27, 2020 04:56



So cool! Beautiful submission.

Posted by muir about 1 year ago (Flag)

That's Great finding......!

Posted by thilinahettiarachchi about 1 year ago (Flag)


Posted by roby about 1 year ago (Flag)

Lovely piece, Cecile.
Your iNat observations are a treasure chest.

Posted by wynand_uys about 1 year ago (Flag)

Long proboscid flies: we have a project for them in the Cape:
Lovely work Cecila!

Posted by tonyrebelo about 1 year ago (Flag)

Congrats Cecile – couldn't agree with you more re the wonderful world of tiny creatures and the Swartland has só much to offer in this regard. Great initiative to record Kasteelberg's biodiversity – enjoy!

Posted by oswaldkurten about 1 year ago (Flag)

Thank you Cecile. Connections to nature are keeping us sane - or as sane as possible! Also, strangely, these connections bring a wee upsurge in creativity, whether directed at nature itself, photography or drawing, say, or at making the meals as much of a pleasure as you reasonably can.

Posted by mags49 about 1 year ago (Flag)

Wonderful piece! Would love to see what a parasitized spider is like.

Posted by janetwright about 1 year ago (Flag)

Wow cool looking :)

Posted by carolr about 1 year ago (Flag)

What a charming fly! Great photo :)

Posted by botanicaltreasures about 1 year ago (Flag)

Nature never ceases to amaze. I love this fly!

Posted by jfkfoxy about 1 year ago (Flag)

Wonderful capture and story. And that sure is one long proboscis! I too am enjoying isolation time finding different bugs and insects in my own garden, I'm amazed everyday! It's amazing what you find if you go looking.

Posted by dlync about 1 year ago (Flag)

What a wild looking fly! It is cute. It looks like something that should be made into a Disney movie.

Posted by walkingstick2 about 1 year ago (Flag)

Really an amazing fly, a great pic, and a great piece of writing too. Thanks so much for teaching us about it all.

Posted by susanhewitt about 1 year ago (Flag)

Although we know it's a fly, my son saw this and thought it should be called the ObesiBee. He likes puns.

Posted by dvanoverbeke about 1 year ago (Flag)

That is so interesting, thank you so much for sharing. I think I photographed these at the weekend - not too successfully, as they are never still!

Posted by debbiebodley about 1 year ago (Flag)

Congratulations, great find and article.....can't wait to do again what keeps you sane: being out observing...!

Posted by tjeerddw about 1 year ago (Flag)

Wonderful vignette, thanks for sharing! I have to confess, when I saw the words "small-headed fly," I instantly thought of the American classic, "Small-headed Flycatcher. Seen Yesterday. He Didn't Leave His Name." by the contemporary nature writer Pete Dunne. "Small-headed Fly" (English-speaking American and Canadian birdwatchers often shorten "flycatcher" to "fly"), written in the late 20th century, is one of the strangest and most wondrous specimens of nature writing I've ever encountered, a work of fiction, indeed fantasy, yet one that leaves you at the end saying to yourself, "Wait. Maybe that DID happen after all..."

Posted by floydted about 1 year ago (Flag)

What an unusual fly!A spectacular photo.

Posted by entoloris about 1 year ago (Flag)

beautiful photo!

Posted by mklubi7555 about 1 year ago (Flag)

hermosa foto !!!

Posted by eduardoingani about 1 year ago (Flag)

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