Slugs overrunning your roses? Try Diatomaceous earth. Here's what Doc & Katy Abraham, in Green Thumb Wisdom: Garden Myths Revealed! have to say: Diatomaceous earth is an abrasive dust with razor-sharp particles formed from the fossil remains of prehistoric algae. Its abrasive effect causes the slugs to dehydrate by losing too much water. It appears to be completely digestible by earthworms. Diatomaceous earth is also harmless to birds, bees, and mammals. It even contains a number of beneficial trace minerals and is a component in some commercial insecticides. You can buy the material in any garden store. Scatter the material around the base of your plants -- slugs absolutely won't go through it!