Slugs are real pests, because they eat both vegetables, especially lettuces and plants, especially hostas. In this case, vinegar acts as a poison to the slugs because, if you spray slugs with it directly, they will die. You can treat snails in exactly the same way. However, because vinegar is also a herbicide, be careful where you spray your vinegar. Salvias for example will die, if they are sprayed as a casualty.