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#1 2017-08-18 20:16:51

Kalitechnis
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Name: Peter
From: Bath
Registered: 2017-08-18
Posts: 13
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Please can anyone identify this weird Back-to-Front Hoverfly...

Hello all,

My first post...I am a keen new macro photographer. (I have been attracted to hoverflies for a long time).

I have seen this weird fly a few times in our local botanical gardens...shown in the attachments below.
I think it must be a hoverfly, as it hovers. It approaches you rear-end to the front... it's hairs catch the (sun)light (the second/middle image) making the fly appear much bigger...and threatening, with its rear legs stretched out, appearing like front legs - as though it's ready to attack! (All it's other legs are pulled up tight to it's body, as can be seen in the other photos)

But, as you can see, it's just a little non-descript fly.

I cannot find any mention (nor images) on the internet of this back-to-front imposter!

Any help identifying said fly would be greatly appreciated!

Thanks,
Kalitechnis


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Last edited by Kalitechnis (2017-08-18 20:21:49)

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#2 2017-08-18 20:24:45

conopid
DF Members
Name: Nigel Jones
From: Shrewsbury
Registered: 2008-02-27
Posts: 630
Website

Re: Please can anyone identify this weird Back-to-Front Hoverfly...

That looks very much like Eristalis pertinax


Nigel Jones
Shropshire

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#3 2017-08-18 20:40:19

Kalitechnis
Registered user
Name: Peter
From: Bath
Registered: 2017-08-18
Posts: 13
Website

Re: Please can anyone identify this weird Back-to-Front Hoverfly...

Yes, it looks similar, and thanks for the input, Conopid.
However, I don't see any fringe of yellow/orange hairs surrounding each eye, as with my "BTF" fly.
Nor is the rear of the abdomen the same..Eristalis pertinax seems to have a pointy rear-end, where-as my BTF fly's is blunt.
Nor can I find any mention of it flying/approaching backwards mimicing a much larger insect/bumblebee.

I might be wrong, but I feel it is a different fly.

Thanks all the same,

Kalitechnis

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#4 2017-08-18 21:27:51

Kalitechnis
Registered user
Name: Peter
From: Bath
Registered: 2017-08-18
Posts: 13
Website

Re: Please can anyone identify this weird Back-to-Front Hoverfly...

I must say, having browsed most of the other posts on this forum, re: E Pertinax, the following photo does look more like mine (most others don't):

http://www.dipteristsforum.org.uk/postg … 282%29.JPG  (Sorry, I've tried using BBcode, to no avail).

The rear end is blunt, and does appear to have a fringe of hairs around the eyes...I may have to eat humble pie!

If it is E Pertinax, where can I find any literature stating it flies back to front, which gives it an altogether different appearance?
(It is this behaviour that time and time again brought this non-descript little fly to my attention.)

Many thanks, and my sincerest apologies if you prove to be correct, Conopid.

K.

Last edited by Kalitechnis (2017-08-18 21:28:49)

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#5 2017-08-18 21:43:35

Kalitechnis
Registered user
Name: Peter
From: Bath
Registered: 2017-08-18
Posts: 13
Website

Re: Please can anyone identify this weird Back-to-Front Hoverfly...

And this one also seems to confirm your identification Conopid:

http://www.wildlifeinsight.com/6057/bri … -pertinax/

My gorilla Avatar pic is already eating humble pie, as I am....

K.

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#6 2017-08-19 00:41:18

Stephane Lebrun
Registered user
Name: Stephane Lebrun
From: Le Havre, FRANCE
Registered: 2008-04-05
Posts: 594

Re: Please can anyone identify this weird Back-to-Front Hoverfly...

E. pertinax it is. wink

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#7 2017-08-19 16:02:10

KenMerrifield
Administrator
Name: Ken Merrifield
Registered: 2008-02-21
Posts: 221

Re: Please can anyone identify this weird Back-to-Front Hoverfly...

Could it be that it was just manoeuvring as part of its display flight and not intentionally interacting with you? In your central picture if you cannot see it's eyes presumably it cannot see you.

Great images BTW
I have never managed to get anything nearly as good

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#8 2017-08-19 22:29:16

Kalitechnis
Registered user
Name: Peter
From: Bath
Registered: 2017-08-18
Posts: 13
Website

Re: Please can anyone identify this weird Back-to-Front Hoverfly...

Ken, thank you for your reply, question and compliments.

No, it definitely has always flown this way towards me ...from far off...and it will circle around maintaining the back-to-front attitude.
I would never have noticed it if it had been flying face forward. It was it's size and weirdness (something not quite right, struck me right away, on my first siting)

As I said it seems much bigger than it actually is, due to the light reflecting off it's body hairs, as you can see. I was only able to take the other photos (from the side and from underneath, by shere persistence, and a lot of patience.

You say that presumably it cannot see me...well my response to that is that it's eyes are big and on it's periphery it can most likely see "behind", at least when it is just slightly off directly back-facing..I have a photo like this (see attached photo) and a sliver of eye can be seen - most likely enough to guide it...

Anyway that's all I can think of...

Has this kind of behaviour never been documented/witnessed by anyone else?

I hope to be able to get to the bottom of this with all your help on this forum.

Many thanks,

Peter


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#9 2017-08-19 22:42:52

Kalitechnis
Registered user
Name: Peter
From: Bath
Registered: 2017-08-18
Posts: 13
Website

Re: Please can anyone identify this weird Back-to-Front Hoverfly...

I am adding another similar photo to the last, but with the (sliver of) eye now more in focus...


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Last edited by Kalitechnis (2017-08-19 22:43:50)

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#10 2017-08-19 23:00:44

Kalitechnis
Registered user
Name: Peter
From: Bath
Registered: 2017-08-18
Posts: 13
Website

Re: Please can anyone identify this weird Back-to-Front Hoverfly...

Oh by the way, merci Stephane pour avoir confirme l'identification.
Have you by any chance seen the behaviour I describe and which can be seen in my photos?

Peter.

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#11 2017-08-19 23:15:13

Kalitechnis
Registered user
Name: Peter
From: Bath
Registered: 2017-08-18
Posts: 13
Website

Re: Please can anyone identify this weird Back-to-Front Hoverfly...

And here's another (a bit over-sharpened) of the rear view clearly showing the eye.
It dropped it's guard here..totally non-threatening!

Yes, I'm still pretty sure that it thinks it is a stinging bee/bumblebee, and that this is the evolved imitation behaviour of this sub-species.

I'm no expert, and await (on tenterhooks!) any confirmation/clarification of my observations.

Peter


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Last edited by Kalitechnis (2017-08-20 10:26:25)

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#12 2017-08-20 13:27:27

Kalitechnis
Registered user
Name: Peter
From: Bath
Registered: 2017-08-18
Posts: 13
Website

Re: Please can anyone identify this weird Back-to-Front Hoverfly...

And here's another one, again a bit over-sharpened in order to more clearly show the eye.

I'm sure that it will be able to see behind from this angle...


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#13 2017-08-20 16:51:30

KenMerrifield
Administrator
Name: Ken Merrifield
Registered: 2008-02-21
Posts: 221

Re: Please can anyone identify this weird Back-to-Front Hoverfly...

If it is still about and you could get a video of this behaviour it would be useful to show to specialists in case they have seen anything similar.

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#14 2017-08-20 17:14:54

Kalitechnis
Registered user
Name: Peter
From: Bath
Registered: 2017-08-18
Posts: 13
Website

Re: Please can anyone identify this weird Back-to-Front Hoverfly...

Yes, I was thinking of doing just that..thanks Ken. Not that I'm used to doing video, at all.
When I get the chance...

I hope that no-one thinks this is a hoax, as it certainly isn't! I wouldn't waste my precious time on such a thing.
I am only posting here as I cannot find any similar images or text describing what I have witnessed and photographed.
Surely someone else must have witnessed this as well...

This has got me going (I see that "pertinax" means persistent, tenacious...well this is bringing out the pertinax in me!

I look forward to any other thoughts on this seemingly unknown behaviour/adaptation.


Peter

Last edited by Kalitechnis (2017-08-20 17:45:22)

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#15 2017-08-21 00:12:35

Kalitechnis
Registered user
Name: Peter
From: Bath
Registered: 2017-08-18
Posts: 13
Website

Re: Please can anyone identify this weird Back-to-Front Hoverfly...

I am uploading a photo of the first Hoverfly that showed this behaviour (below) that I have just re-discovered
It was 2 years previous to the the one shown above, and was basically forgotten (as it was taken from pretty far away and has been greatly cropped)

As you can see it's another sub-species...would it be a male Eristalis Arbustorum?

It too, approached Back-to-Front, from afar...and I immediately thought it looked odd.

My first thought on seeing it in my binocs (that it was flying backwards, and circling around me, mostly maintaining the Back-to-Front position, was that it is a strategy to approach and inspect the invader of territory, and flying backwards means a quicker means of escape from potential danger.
But, as it too looked bigger than it's real size (in this fly's case, because it's abdomen, seen from afar, looks like a large head with large eyes, (and again, those extended rear legs...), I figured it is mimicry (as well as a quicker escape?).

It was this that attracted me to it, and made me take photos of it.

I actually thought both sets of photos were of the same sub-species of hoverfly, but now it would appear that at least two members of the hoverfly family show the same curious behaviour/mimicry, dare I say?

Hope this is not too long for everybody...I'm trying to be as succinct as possible.

My thanks for any other comments from anyone,


Peter


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#16 2017-08-22 15:58:06

KenMerrifield
Administrator
Name: Ken Merrifield
Registered: 2008-02-21
Posts: 221

Re: Please can anyone identify this weird Back-to-Front Hoverfly...

My guess would be a male Eristalis intricarius, males often hover holding a territory, presumably watching for females approaching and chasing off males, and sometimes other insects, that enter their territory.

Steve Falk mentions territorial behaviour on his flickr page-
https://www.flickr.com/photos/63075200@ … 600153789/

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#17 2017-08-23 00:03:53

Kalitechnis
Registered user
Name: Peter
From: Bath
Registered: 2017-08-18
Posts: 13
Website

Re: Please can anyone identify this weird Back-to-Front Hoverfly...

Thank you Ken for your input and identification of the last photo...

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