Just figured I'd throw this out there. Your mileage may vary.

The Worm Inn is totally enclosed with a fine mesh lid. Flies can't get in, flies can't get out. When I first got flies, I immediately started freezing my scraps and setting up traps in the worm inn. Lesson learned. The problem is that the enclosed nature of the worm inn makes it reaaal easy for the flies to mate, and even though I was catching hundreds a day in the apple cider vinegar mix, they just couldn't be beat with that alone.

Then I started vacuuming. I half covered the lid with plastic wrap and vacuumed through a small opening, creating a wind tunnel in the worm inn and sucking all of them out of the air. This worked well, but it was quite labor intensive to do this every few hours. I still didn't get ahead of them.

Eventually, I used a larger vinegar trap. It was a paper tray and it took up half the surface area of the worm inn. It got tons of flies, but still not enough - and this caused a side issue, heat began to build up underneath it. So to curb the heat, I wet down the bedding real good and took a 120mm computer fan to it. The computer fan was easy to hook up, I dug through my adapter collection and found a 12vdc adapter, soldered some wires together, installed a mesh guard on the fan to protect the worm inn from the blades, and put some soft tape around the edges of the fan so it wouldn't cut through with its own weight.

Well, it cooled the hot area right down. My normal procedure was to agitate the flies by tapping the sides of the worm inn, then vacuum flies up as I opened the zipper of the trap. This time though... tapping the sides of the trap didn't agitate any flies. There were none standing around anywhere. I slowly opened the trap, ready to vacuum... and no flies to be seen. As I wet down the bedding again, which had dried up, a few came on out and I vacuumed those right away, but I had nowhere near the quantity of before.

It seems as though the moving air prevents these small flies from getting around too easily. They can't mate too easily. They're hatching, and staying in the bedding where they'll eventually die and decompose.

I proclaim a tentative victory.