But, really, it depends on what fly she was trying to catch...because this one is a spider killer.
OK, I can hear you argue, its a wasp, not a true fly...and you are right, it is a spider wasp (Auplopus).
I have noticed in the last week or so a lot of the wasps hunting the huntsmen spiders; so I spent a few hours hunting the hunters of the huntsmen.
You can see from these photos the typical behaviour of leg amputation, to make the prey easier to carry. The paralysed hapless prey is then carried off to feed the babies of the wasps, or they are laid directly into the body of the spider itself.
I have also noticed that they carry their prey with the mandibles wrapped around one of the large fangs, as in this photo below; presumably to avoid any mishaps.
ps shout out to Sasha Haldane as you might notice the background of a railing...and these are a great place to find these hunters, which was introduced to me by spider woman