My intuition is to go with boric acid, in the garden, not borax since it is more plant available, and also borax contains sodium. H2BO3- borate probably behaves like phosphate in soil, not very mobile.
I might try the borax sparingly on the lawn. I dont want to kill all the ants. They do a good job aerating the soil. As an aside I find that mopping the kitchen floor with a little borax seems to make carpenter ants disappear.
|