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Kleptoparasitism ! -Freeloader Flies

Family: Milichiidae

Photo by Leuba Ridgway
Published on Project Noah
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Field Notes

Description:

Tiny flies about 2 mm long with shiny thorax and red eyes, all over a curled leaf shelter of a spider. The shelter appeared to be a single broad gum leaf folded in an "L" shape and bound by silk, except for the lower end which served as an opening through which the spider could exit the shelter. The leaf was suspended in the air by a fantastic delicate webbing of silk strung from plant branches of nearby shrubs.
The spiders legs can be seen protruding from the lower end in Pic 1.

Habitat:

Spotted in a nature reserve.

Notes:

This was an amazing sight with so many apparently ready morsels of food at the spider's doorstep ! but these flies were waiting to steal some of the spiders food, which would have been any number of tiny insects. An example of kleptoparasitism.<br>
When I touched some of the webbing, a fat abdomen spider came out quite fast probably to check if anything was caught in the web. It made a quick retreat so I could not get a shot of it. <br>
The flies stayed clearly away from the spider, resting on the silk-covered shelter. How they don't get tangled in the webbing around the shelter is something I would like to know ! <br>

I am not able to get an ID past the Family : Milichiidae <br>

https://sites.google.com/site/insectsoftasmaniadiptera/suborder-brachyc…

Here's a spotting by folicallychalled showing a similar relationship between spider & fly
http://www.projectnoah.org/spottings/31155071 <br> 6 eyars later I've, just by chance, been able to get an ID for the spider. Thanks to James Patullo. The spider happens to be Phonognatha graeffei, a leaf curling spider from Family: Araneidae

Species ID Suggestions

Comments (7)

The 2nd and 3rd images of the link show the cleaning. At the time, I did not know what I was photographing, otherwise I would have done better. Dave
"..the fly cleaning the spiders mouth parts" - that is un-real!!! would love to see that. Somehow I think these little flies are hanging around for the left overs. I will re-visit the place soon to check on the spider but I fear that the recent 2 to 3 days of rain might have done the shelter some damage. Your spotting is precious, Dave. Thanks for the information and feedback.
If this is close by, I think it would be worth some study time. The flies are attracted by enzymes released when the spider is feeding. The flies will suck up the fluids that the spider creates. As far as I know, that image of mine is the only one of the symbiotics, with the fly cleaning the spiders mouth parts. You may have an opportunity to do better. Dave
Thanks for the cross-link, folicallychalled. Good to have this on my spotting. I agree that they may be related. I did see your amazing spotting but it's wonderful to see it for yourself ! It's a pity I could not get a shot of the spider. Still this behaviour is what it's all about, is it not?
Great find and very interesting. Probably closely related to this unidentified fly: http://www.projectnoah.org/spottings/31155071 Dave

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