I recently tried one out after a nasty thrip problem on my last grow. Before I started my current garden, I shut off all airflow to the room and placed a no pest strip in the center of it. Left for about a week, the room smelled strongly of insecticide. That was 6 weeks ago and I haven't seen so much as a fungus gnat in that room. I personally think they work very well, though I'm unsure of their effect on flowering plants.