When I was a teenager, I got a job at a local Cineplex Odeon theatre and they had this wonderful stuff called gum remover. It came in a can and it was like poor man's liquid nitrogen. You'd see gum squished into the carpet and you'd spray it with this stuff, freezing the gum and then you could dislodge it with one kick of your shoe. It had other uses. Freezing houseflies in mid air in order to capture and domesticate them.
What you did was, chase the pesky fly down with the gum remover, freeze him in mid flight, pick him up off the floor and tie a bit of thread around his abdomen. It took a few times (and flies) to get it right. The most common mistake is cutting the fly in half when you tighten the knot. I prefer a rapalla knot for this type of work. You also can't use too much thread or it causes a payload problem and Mr fly can't get air born. When you have the length just right you end up with a fly on a 6 inch thread leash. You can tie it around his head but watch out for accidental decapitations. I seem to recall having the thread trail the underside of the fly as being workable. You also have to watch the damned legs (they always get in the way!)
A leashed fly lasted about a day. I don't know what flies eat and it may have starved to death. I wasn't about to go outside and find dog droppings or whatever they are partial too.
All this for $4.15 an hour! Woohoo!