are boric acid for ants and roaches, DE also for crawlies, and bt for caterpillars

none of the "organic" fly sprays has worked, nor mosquito repelents

For fruit flies, which I get an explosion of occassional, I make homemade fly traps from soda bottles. You can see instructions here.

http://mudnessa.blogspot.com/2011/06/diy-fruit-fly-trap.html?m=1

To attract the flies, you can use apple cider vinegar and a drlop or two of dish washing liquid, like Dawn. I've also made them with fruit juice and even with water and a packet of Emergen C. Always use a couple of drops of Dawn. It breaks the surface tension of the water so when the flies land, they drown.

Also, fruit flies breed in the moisture of your kitchen drain, so always keep the drain stoppered.