Will boric acid work for bed bugs?

No.

Boric acid is a dust stomach poison that gets picked up on the pest’s body and ingested when the pest cleans itself. Bed bugs don’t clean themselves and don’t have mouth parts to do anything but suck blood. So boric acid doesn’t work on them as a stomach poison.

Note that cockroaches and ants don’t eat piles of boric acid, even when it’s mixed with sugar. The Pest Management Professional should apply dust formulations in a very light coat—if you can see dust, it’s probably too much. Follow the label directions.