Scary good. I put the traps out where I have seen ants in the house (big black ones, I am in Canada, 3hrs north of Montreal). The ants started swarming on it, which is scary. I had to leave the room not to panic and kill them on sight (they need to bring the poison home, so you can't stomp on them). Within 36 or 48 hrs the ants stopped coming so I moved the trap to another part of the house. Then I saw a new swarm of the smallest ants I have ever seen where the traps had initially been. (!!) I am assuming this is the new generation of the colony that were born when the adults died and followed the tracks to the source of food (my traps!). So I put the traps back and spilled a little of the poison directly onto the window ledge where they were gathering. They all "drank" around the spilled poison like animals around a watering hole. There were a LOT of them. I have ordered more, and will place them in different areas of the house. This time I will leave the traps even after I stop seeing the adults, in case there are more generations following behind. This is the most effective poison I have ever seen. The transparent trap is very useful, because you can see if they are inside, where the little metal pods I used to buy you could never know if there was any poison left, or if there are ants inside. Much better this way.