I may have started my intervention too late, but I can see that the BTI solution works. At least now I’ll know what to do at the 1st sign of gnats in the future. Great online info & tutorial, too. Bless you. My beloved indoor palm tree probably didn’t have proper drainage in the 1st place & became infested with spider mites, too. Going at with all of your suggested arsenal. Had to chop off leaves. Will repot & see if it can be salvaged. Fingers crossed!