The only thing that I know of that actually works (other than the guillotine!!) is castor oil. It is expensive, but they don't like it. If you have a small enough yard, you can just use a spray bottle to cover your grass. They eat the roots and since they don't like the oil, they won't have any food and will move onto...your neighbor's yard!!! This is also a very environmentally friendly cure...won't hurt your yard, children or animals.