When I look up boric acid on the net there are various ads for it to kill roaches but no explanation of why it is effective on roaches. I am in East TX , roach central. When my house was built I put pounds of boric acid in between the studs before drywall went up . For 25 years I don't think I saw a dozen roaches in the house. But starting this spring ,I have killed a few roaches every night . As if they became immune to the boric acid ( as much as I put in ,it could not be gone). We have pets so I am reluctant to use insecticide in the house.