Predator and prey

in #butterflydaylast year

robber fly.jpg

The Robber fly has caught a Black Soldier fly and used her mouthparts to pierce the thorax of the soldier fly and feed on its body fluids.

Let's take a look at them in more detail:
Firstly, the predator is very common in the garden, probably a member of genus Daspletis although they more commonly prey on bees and wasps. The one above is a female and the one pictured below is a male. You can see the large genital appendage at the end of his abdomen

robber fly1.jpg

The one below is a female, like the fly in the first picture


Looking at the hairs and hooks on the legs, its clear that this is a predator that pounces on prey in flight and doesn't let go easily. The piercing mouthpart is also visible.

On to the prey:

hermetia illucens.jpg

Hermetia illucens or Black Soldier flies are highly beneficial insects for a gardener. The adults seldom feed and survive only to mate and lay eggs. The larvae feed on rotting vegetable matter but unlike other fly species their body secretions don't promote bacterial rot so they break down compost without causing an unhygienic smelly mess. The adults are also not bacteria carriers so having them around doesn't promote unsanitary conditions.

hermetia illucens larvae.jpg

These strange looking creatures are pupae of the flies and despite the fact that they don't have legs, they travel easily through rotten vegetable matter with an undulating motion of the segments.

Black soldier flies are wasp mimics, which protects them from predators such as birds or toads but not other insects that normally prey on wasps.

All images my own

Identification - Picker, Griffiths, Weaving: Field Guide to Insects of South Africa
Black Soldier Flies on Wikipedia


What a grisly beginning to a wonderful blog. If you never wrote a word, the pictures alone would be fantastic. But your description, may I call it a lesson (for me), is fascinating. I will no longer disdain flies as a category. Black soldier fly (why soldier?). The best part I think was the description (and picture) of the pupae.
Reblogging this wonderful post...and sharing on Twitter. Hope the picture shows up there. Catch more 'flies' that way :)

Thanks! Flies are a very important part of an ecosystem. I can't answer why it is called a soldier fly

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Thank you!

Interesting to see and read. They must be grateful that their gardener knows so much about them :D

Nah, they just go about their lives

Thanks for sharing your experience with us!

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A very interesting post about the life of insects.

Very interesting I learn something new - about flies, today. 😊

Flies are an extremely important family of insects

I understand. Thanks for you reply.

Awesome insight into your garden 😍
I have had soldier fly larvae in an above ground compost before, they do a great job!!

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Excellent creatures. My brothers were keen on farming them at one stage

it's mating season huh

Great photos and an interesting post!


You just got to love beneficial insects. I am jealous that you found a robber fly with its prey and a fly grub. Lucky you! Great photos too. Thanks for using #butterflyday tag @nikv. : )
I posted male and female robber flies a couple of weeks ago but your photos are so much better.

Your influence, far and wide :)

Thanks for making me smile AG! : )

Happy New Year, friend.

Thanks, my friend AG! Wishing you a healthy and happy New Year and New Decade! Hugs!

I'm smiling too ! :)

@agmoore always makes everyone smile with her wonderful comments. : )
Keep smiling! : )

Far & wide - yes indeed !!!!!!!!!!!!

Thanks, I remember your flies, that's where I first learned to tell the difference :)
There are so many fat, lazy robber-flies in my garden, they are very easy to photograph. They hang around hunting bees and wasps, which are plentiful too

I am happy to hear that I could help. I love it when people learn something from my posts. : )
It is good to know that you have so many bees and wasps. I am worried about their decline.

I try my best to stay away from routine pesticide use. Sigh

Yay! I am very happy to hear that. : )

Saludos. Muy buenas imágenes amiga @nikv. Y la información me encanta. Puedo ver esta mosca negra en mi jardín y no sabía que era beneficiosa.

Greetings. Very good images friend @nikv. And I love the information. I can see this black fly in my garden and I didn't know it was beneficial.

Thank you :) I also learned about them recently. I don't usually see so many but they were feasting after I cut the ombú tree down and it started to rot

Ah una fiesta de oportunistas jejejeje.

Ah a party of opportunists hehehehe.

Absolutely amazing pictures @nikv

Thank you!

Amazingly clear photos :-)

Thanks! The cellphone has its uses ;)

Wow! More scary than snakes!!

Not really, none of these creatures bite humans

Okay! But they don’t look very attractive! LoL
They need a face lift!

No, they are perfect as they are!

Nature is amazing and harsh!