A Dipteran Army

Twin-spot Centurion (Sargus bipunctatus) Photo by Leo Smith

Dear Readers, I do love it when people ask me to identify insects, and I love it even more when it’s a creature that I haven’t seen before. So today, I’d like to introduce you to the family of soldier-flies, rather splendid creatures that can go completely unnoticed. My friend Leo spotted this one at the nature reserve at Gunnersbury. At first glance you might think that it was a simple greenbottle, but have a look at those fine orange legs, and the narrow pointed abdomen. Plus, the ‘twin-spot’ centurion has two white spots just in front of the tiny short antennae. Furthermore, females have a bright orange patch on the abdomen, and, as this fly doesn’t have such a thing, we can safely assume that it’s a male.

There are 48 soldier fly species in the UK, and they  were so named because their bright colours reminded people of ceremonial uniforms. The smallest ones are referred to as soldiers….

Photo One This image is created by user Dick Belgers at waarneming.nl, a source of nature observations in the Netherlands. / CC BY (https://creativecommons.org/licenses/by/3.0)

Three-lined soldier (Oxycera trilineata) – 6mm (Photo One)

Then we have the majors…

Photo Two byJanet Graham / CC BY (https://creativecommons.org/licenses/by/2.0)

Four-banded major (Oxycera rara) 7mm (Photo Two)

Then the colonels…

Photo Three This image is created by user Dick Belgers at waarneming.nl, a source of nature observations in the Netherlands. / CC BY (https://creativecommons.org/licenses/by/3.0)

Common green colonel  8mm (Oplodontha viridula) (Photo Three)

Then the brigadiers….

Photo Four This image is created by user B. Schoenmakers at waarneming.nl, a source of nature observations in the Netherlands. / CC BY (https://creativecommons.org/licenses/by/3.0)

Ornate Brigadier (Odontomyia ornata) 12-14mm (Photo Four)

And finally the generals (though there are a few legionnaires and centurions about too, who don’t fit neatly into any of the size categories).

Photo Five by Siga / CC BY-SA (https://creativecommons.org/licenses/by-sa/3.0)

Clubbed general (Stratiomys chamaeleon) 12-15mm (Photo Five)

Now, have a good close look at the back of the Clubbed General (the last photo in the series). On the yellow ‘bit’ just above the wings (known as the scutellum) you’ll see two spikes sticking out. This was another reason that the group were known as ‘soldier flies’ – they seem to be carrying their own spikey armour. In Germany, this family are known as Waffenfliegen or ‘armed flies’. Different species of soldier fly have a different number of spikes, and this is a way of identifying the flies.

What spectacular flies they are! The adults zip about pollinating wild carrot and hogweed, but it’s the larvae who really do the work – they consume ridiculous amounts of dead and decaying matter, everything from algae in ponds to rotting vegetation. One species, the black soldier fly (Hermetia illucens) is widely used as a way to consume the dung produced by poultry farms. The waste is fed to the larvae of the soldier flies, who then pupate. The pupae are then fed back to the chickens. This is an incredibly efficient process: the eggs turn into larvae in just four days, and by the time that they pupate, the larvae have taken chicken manure and converted it to 42% protein.Levels of e-coli and other bacteria go down when the larvae are used to clean up the waste. Black soldier fly larvae are also being used in fish farms and to feed exotic animals that are kept as pets.

The adult soldier flies are extremely relaxed creatures, who neither bite nor sting and are apparently very easy to catch, and this seems to be their downfall. It does just show, however, that without the detritivores of the world munching up our waste, we’d soon be buried in the stuff. We have much to thank flies for.

Photo Six byBy Didier Descouens - Own work, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=29228852

Black soldier fly (Hermetia illucens) (Photo Six)

Incidentally, my go-to books on flies (everyone should have a go-to book on flies I think) are both by Erica McAllister – the first is ‘The Secret Life of Flies’ (from which many of the facts here have been extracted) and her new one is ‘The Inside Out of Flies’, which is about the structure and anatomy of flies. Both are fascinating and great reads to boot. If you’ve never considered the humble fly before (or your first reaction is to wap them with a rolled-up newspaper) these books might give you pause.

Finally, two remaining facts about soldier flies, courtesy of Erica. Firstly, she calls soldier flies ‘fat-bottomed flies’, as some species have abdomens that are almost as wide as they are long. The Ornate Brigadier photographed above is pretty well-endowed on the back-end front, and so are the generals though the angle is wrong for the one in the photo. There is an African species called Platyna hastata where the rear-end is actually wider than it is long, but I can’t find a photo, sadly. Suffice it to say that if a stripey creature which is broad in the beam lands next to you, it might well be a soldier fly.

And finally, one species of soldier fly has the longest Latin name on the planet: ‘Parastratiosphecomyia stratiosphecomyiodes‘ which roughly translates to ‘near soldier wasp-fly wasp-fly like’. And here is the poor little thing. I think someone must have been having a laugh.

Photo Seven by Norman E. Woodley / CC BY (https://creativecommons.org/licenses/by/3.0)

The animal with the longest name in the world (Photo Seven)

Photo Credits

Photo One This image is created by user Dick Belgers at waarneming.nl, a source of nature observations in the Netherlands. / CC BY (https://creativecommons.org/licenses/by/3.0)

Photo Two by Janet Graham / CC BY (https://creativecommons.org/licenses/by/2.0)

Photo Three This image is created by user Dick Belgers at waarneming.nl, a source of nature observations in the Netherlands. / CC BY (https://creativecommons.org/licenses/by/3.0)

Photo Four This image is created by user B. Schoenmakers at waarneming.nl, a source of nature observations in the Netherlands. / CC BY (https://creativecommons.org/licenses/by/3.0)

Photo Five by Siga / CC BY-SA (https://creativecommons.org/licenses/by-sa/3.0)

Photo Six By Didier Descouens – Own work, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=29228852

Photo Seven by Norman E. Woodley / CC BY (https://creativecommons.org/licenses/by/3.0)

7 thoughts on “A Dipteran Army

  1. Alittlebitoutoffocus

    Fascinating stuff, as always. (I particularly liked the “….back end front” which amused me). I shall have to check the little critters out before I whack them with the swatter next time and maybe, just maybe, one or two might just get a reprieve.

    Reply
  2. Ann Bronkhorst

    Two words/phrases to relish: ‘detritivores’ and ‘well endowed on the back end front’. Must find ways to drop them into conversation.

    Reply

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