For an active Drywood termite infestation, mix 1 gallon of BoraCare with 1 gallon of water.
One gallon of Bora-Care will treat approximately 100 lineal feet of 2 x 4 stud wall. Typically, one gallon of concentrate Bora-Care will treat 800 square feet of a 2x4 stud wall, and 500 square feet of a crawl space or attic.
Depending on how big of an area and what specifically you are treating for drywood termites (floors, furniture, crawlspace,etc) will depend on how much BoraCare to use.