It has also appeared in roses in my house. I tried many methods but failed. In summary, I tried the methods myself: 1. Buy medicine 2. Use cigarettes to soak in water. The thicker the better. 3. Use bleach water and soapy water to make it thick and pour it down (I am currently experimenting with this method. It seems that the snails are dead these days, but the flowers seem to be withering soon... I hope it will get better)