pet barriers, which latter are used by pet owners to confine their own pets to designated areas. Flashing lights are used to repel lions in Kenya. The ideal repellent is completely specific for the target animal; that is, it drives away the animal that one wishes to repel without affecting or harming any other animals or people. One type of animal repellent may be effective for raccoons, while another animal repellent may be more effective for skunks. It can be difficult to design a repellent method that drives away only undesirable animals while having no effect on people or other creatures. Snake repellents Research has shown that cinnamon oil, clove oil, and eugenol are effective snake repellents. Snakes will retreat when sprayed directly with these oils and will exit cargo or other confined spaces when these oils are introduced to the area. In ancient times the Greek historian Herodotus noted that Arabian harvesters of frankincense used burning resin from Styrax trees to repel poisonous snakes that lived in the trees. Camphor Moth balls The roots and other parts of Acacia polyacantha subsp. campylacantha emit chemical compounds that repel animals including rats, snakes and crocodiles. For snakes, roots are placed in the rafters of houses. See also Bird control spike Cat repellent Electronic pest control Insect repellent Shark repellent Chemical ecology References External links Pest control techniques Chemical ecology Horticultural techniques Agronomy Habitat management equipment and methods Organic farming