Ross
I don't think your flies will go on fire. The pastry crust on a pie does not go up in flames in an oven at 1900, certainly not after 2 minutes. The ignition temperature of paper is around 2300.
I would test samples of things like mylar tinsel, rubber legs, flexifloss and other artificial materials first before I put a tied up fly in the oven.
cheers
Irvine