Parasites can be found in every environment on earth and infect a wide range of hosts - birds, fish, plants, insects, wild animals, domesticated animals and humans. When parasites are discussed they often trigger an "ewww" reaction. However, they have much more serious economic, food security and animal health and welfare impacts when they infect grazing livestock. Grazing livestock contribute greatly to food security and this is not going to change any time soon. Not only is the global population (and therefore food requirement) growing, there is an increasing demand for animal-based food products in developing regions and there is an essential role of animal products in marginal environments where crop production is infeasible. Parasite control is therefore vital, but is not easy to achieve.