how about putting the plant in the fridge (if you have a spare, empty fridge...) not cold enough to kill the plant, (some stress) but it slows the plants processes, think clones or fresh-cut flowers :stoned:; cold enough to kill most any insect found on plant or in soil, check the fridge temps first though;
an hour or so of the low 40's should do the trick; or at least break the life cycle in more than one stage.