Bait: 10 percent of boric acid mixed with 90 percent of the filler. Use mashed potatoes, biscuit crumbs, cereal or egg yolk as a filler. This "delicacy" is deadly for cockroaches. Moreover, if you add the yeast you can be sure that the insects try to eat this. Trap: Put a piece of white bread soaked with beer at the bottom of a jar (cockroaches are absolutely crazy about the beer smell!!!). Tie a bandage round the neck of the jar and soak its end with beer. Put the jar on the floor...