Substral Celaflor Pest Free Careo Combi Sticks, 2-in-1: Plant Protection and Fertiliser Function, Pack of 40, Insects

This is very effective for indoor plants. I had three plants which developed fungus gnats, those annoying little black flies that don't bite humans but eat plant roots as larvae, I believe they incubate in the soil itself, so something to go into the soil seemed a good idea to exterminate the critters.In the parcel there are two packs of 20 sticks in each. Initially I broke one stick into three pieces and put them in the three affected plant pots.Instant carnage, I assume so anyway, the flies just died away over the next day or two and stayed away for about two months.When they began to come back I repeated the process of breaking one stick into three and putting it in the plant's soil.The flies disappeared again, so I can say with confidence this is a good effective product and these forty sticks will last a while!