I was seeing a lot of mosquitoes this summer and decided to give this a try. I filled up a bucket, added some branches and leaves, and dropped one of these in. I also placed one in my rain gutter drain area and a few other spots. They definitely worked—I noticed little to no mosquitoes just a couple of days later. However, I did start to see them reappear after about three weeks, though still not nearly as bad as before. As long as you add new ones every few weeks, it should take care of your mosquito problem, as it did for mine. I do find they are a bit pricey for what it is.