Gallery Links
Users Online
· Guests Online: 23

· Members Online: 0

· Total Members: 4,988
· Newest Member: DedeLab
Forum Threads
Theme Switcher
Switch to:
Last Seen Users
· evdb< 5 mins
· smol00:12:35
· piros00:33:15
· weia00:36:31
· Sundew00:46:20
· DedeLab00:56:52
· serenense701:00:06
· Juergen Peters01:01:10
· Stephan Mende02:01:35
· Joerg Schneider02:06:54
Latest Photo Additions
Female swarms of Phalacrotophora (Phoridae)
In June and July, I spotted a swarm of Phalacrotophora (Phoridae) flying about the bases of Acer pseudoplatanus and Fraxinus excelsior trees in mixed woodland near Norwich, England. Phalacrotophora swarms have been recorded before, but their function has always been a bit of a mystery. I identified the flies as Phalacrotophora delageae Disney, a species that has not been found in Britain before.
I will be writing a short paper adding this species to the British fauna, and describing my observations, but Diptera.info seems to be the perfect place to post a series of photographs which will be too costly to publish in a journal!

The swarms consisted of twenty to thirty females flying between 0.2 and 1 metres above the ground, and within 0.2 metres of the trunk. When undisturbed, up to ten females would settle on the tree trunk, in a ?head-down? posture, eaching one staying like this for up to a minute before settling elsewhere or joining the swarm again. In the ?head-down? posture, the flies extend the abdomen and point it torwards the tree, exposing the membranous patch at the base of the fifth tergite

This photo shows the 'display posture' of a Phalacrotophora delageae female.


The unchitinised part of the tergite appears to glow brightly. It contrasts with the black tergites 2 to 4 in front and the orange of the remainder of the fifth segment.


If the overall brightness is digitally reduced, you can see how much this little fly appears to glow in the dark! I did examine some live specimens in the dark, and under an ultra-violet lamp, but there was no evidence of luminescence or enhanced reflection with UV.


While sitting in this pose, the females vibrate their wings, presumably creating a distinctive sound. Visually this appears to be exactly the same as the wing-waving of Drosophila when it is 'singing'. This sequence shows the position of the wings at different points in the 'song'.


After a while, the females stop their display and sit on projections on the tree trunk (in this case a snail shell) where they interact in a casual way. Then they join the swarm again before landing in the display posture for another session.


I did not see any males at the swarming sites, and could not find any concentrations of coccinellid larvae or pupae close by. So the purpose of these female Phalacrotophora swarms is still a bit of a mystery, but I think that the visually striking display posture, combined with the 'song' and possibly pheromones must be to attract a mate.

After all, to a male Phalacrotophora this female can only be saying 'Come and get me!'

Comments
#1 | Robert Nash on 14 July 2006 16:37:30
Wonderfully observed and photographedPfftPfftPfft. I wonder if the glow protects them from predators and "parasitic" Hymenoptera, prior to dispersal and egg laying? explaining the absence of males.
Also have you seen http://www.fcla.edu/FlaEnt/fe81p282.html Scrambled paper entitled Phototropism, Bioluminescence, and the Diptera? Robert
#2 | Nikita Vikhrev on 07 August 2006 14:23:12
I think that the age of scientific information on paper is over. Internet permits to get information much faster, it also permits properly illustrate it (as in this case) and immediately get comments. I think that www.Diptera.info shows all nesessary characteristics to turn into virtual dipterology jornal.
#3 | Paul Beuk on 07 August 2006 20:10:59
Still, the internet may go down, websites may go offline (God forbid that this one will) but paper publications will be available for centuries to come. I am in favour that information never will be trusted to the internet only.
#4 | conopid on 07 August 2006 21:37:25
Unless people print it off and keep it in a library maybe?!
#5 | Nikita Vikhrev on 07 August 2006 22:06:19
Anyway, it isn't we who decide the future of paper-jornals. But we can make internet jornal never mind "instead of" or "in addition to".
#6 | Robert Nash on 09 September 2006 15:36:42
REFERENCE Bioluminescence in Mycetophilidae
http://www.fcla.edu/FlaEnt/fe81p282.pdf
A pdf Pfft Suggests the light is a prey lure (interesting in view of the fact that many Phoridae are sarcosaprophagous (see Glossary) also states that the light may attract parasites (quite contrary to my suggestion). Are we getting close Tony ? Is this a death trap?
#7 | yaguza on 20 October 2006 14:06:06
Very interestingPfft
To find out how swarm works, Why don't release some male Phoridae nearby, to see if they are lured
#8 | flycatcher on 23 October 2006 00:45:15
Hello Tony,

Very interesting notes and photos. Can you tell me what camera, lens etc. you used.

Thanks,

John Flynn
#9 | Bastiaan Wakkie on 27 February 2007 01:39:23
To comment on the digital scientific information. How about video material? You cant really print this. Like flight or mating behavior.
You just need to backup your digital information properly. And if you allow people to download your digital info the data is spread over the world anyway. I rather have all printed material digital than the opposite I must say. So I can find information much quicker.

But then again trusting on internet solely will not be a good idea for now if your system cant handle 100% availability. (printed papers aren't always available either btw)

Some of my thoughts Wink

Cheers,
#10 | Toby on 31 March 2007 23:41:22
flycatcher - if you right click on top images and then click on EXIF you will see a Canon 350D digital dslr was used with a 60mm lens - probably a CAnon 60mm macro.
Post Comment
Please Login to Post a Comment.
Ratings
Rating is available to Members only.

Please login or register to vote.

No Ratings have been Posted.
Date and time
24 November 2024 20:16
Login
Username

Password



Not a member yet?
Click here to register.

Forgotten your password?
Request a new one here.
Temporary email?
Due to fact this site has functionality making use of your email address, any registration using a temporary email address will be rejected.

Paul
Donate
Please, help to make
Diptera.info
possible and enable
further improvements!
Latest Articles
Syrph the Net
Those who want to have access to the Syrph the Net database need to sign the
License Agreement -
Click to Download


Public files of Syrph the Net can be downloaded HERE

Last updated: 25.08.2011
Shoutbox
You must login to post a message.

21.11.24 04:50
I can no longer send private messages (and maybe not receive?), even though my inbox and outbox are not yet full. I write, click "send" and they disappear and never show up in the outbox.

08.11.24 17:10
Www.abebooks.com

29.07.24 14:19
Don't suppose anyone knows anwhere selling a copy of Contributions to a Manual of Palaearctic Diptera 2? Always wanted a copy.... Smile

16.07.24 12:37
TumbsUp

11.07.24 13:59
Following up on the update provided by Paul on the donations received in 2024, I just made a donation. Follow my example Wink

17.08.23 16:23
Aneomochtherus

17.08.23 14:54
Tony, I HAD a blank in the file name. Sorry!

17.08.23 14:44
Tony, thanks! I tried it (see "Cylindromyia" Wink but don't see the image in the post.

17.08.23 12:37
pjt - just send the post and attached image. Do not preview thread, as this will lose the link to the image,

16.08.23 09:37
Tried to attach an image to a forum post. jpg, 32kB, 72dpi, no blanks, ... File name is correctly displayed, but when I click "Preview Thread" it just vanishes. Help!

Render time: 1.02 seconds | 204,810,579 unique visits