I have since tried the fruitfly container method and it does not seem to do much- perhaps if you added some ground up dog food to it?
Here are a few more links that you might find interesting.
This first one is an informative page with a rearing technique I would not recommend- I just would not use any raw meat in rearing flies.
http://www.adcham.com/html/insects/insects-fly-rearing.html
And here is the method by which those of us who are too cheap to buy flies can obtain them, and their eggs, on a warm day.
http://insected.arl.arizona.edu/flyrear.htm
In order to have the fly trap work well I would recommend tuna juice (from canned tuna) and a milk cap full of milk added to several tissue papers and put in a pop bottle as recommended in the above webpage. Then I would spray it with water every couple of days. Of course- this does not work very well unless it is warm enough for flies to be out and about. The nice thing about this also is that by trapping flies you get a variety of sizes of pupaes and flies in the end.
Here are only a few of the things about breeding houseflies that make it different from breeding fruitflies:
1. They NEED to be kept around 80 degrees or above. If they are not the larvae will not thrive and die off and stench will soon occur.
2. They NEED good ventilation soon after the larvae hatch. (But kept somewhat moist before hatching)
3. They DO NOT need to be kept very moist throughout their life. If it is too moist it will smell like fresh dog poop.
4. They SHOULD NOT have an excess of medium in their container- if there is too much extra medium for the population of larvaes it will stink.
5. They DO need some sort of fiber (wood chips, ground up rabbit food, etc.) on top of their medium to mix with the medium. If there is no fiber the larvae tend to suffocate.
I found that the method for breeding suggested by Spider Pharm (link is on this thread), with some alterations, works well for me in breeding more than enough flies for my mantises. If I ever get down to only spending 2 hours a week on the whole thing I will definitely tell everyone how I do it!