After months of watching my lawn and several shrubs destroyed by gophers (or moles?) with no apparent deterrent effect of several ultrasonic gopher chasers and one failed attempt with a trap (whatever it was pushed dirt into the trap and sprung it), I ordered a package of these. When I found a fresh mound, I opened the hole, lit up one of these, stuck it in, and covered it with a rock (the instructions are accurate--they put out a lot of smoke, and you DON'T want to breathe it). In a few minutes, I saw a wisp of smoke coming out of another, smaller hole about 8 feet away and covered it as well. At that point I was pretty sure I'd found a burrow. It's been well over a month, and I haven't seen another mound. Maybe I just got lucky, but I'm not complaining.