Yes you must also clean and treat coop and areas. In my old post that I shared I used DE, since then I have also added Oragne Guard which works great, I also spray it around my own house for pests. I also sprayed some organic oils around the coop and area that I knew bugs didn't like as a repellant. Great info on the 10min under water guinea fowl galore. I knew the lice drown, I was just going off my experience with flea's, once when I was little the cat's and dog got fleas and we would hold them under soapy water to drown them, if there were no soap the fleas would jump out soap helped them sink and drown.