The role of plants as pest controls In nature certain birds like parakeets bring green leaves, including neem leaves (Azadirachta indica) that contain volatile compounds to their nests in the breeding season for the control of parasites that live outside their host. Studies by Smith in 1974 revealed that the crushed leaves of black sage had a strong aromatic odour similar to a pyrethrum extract. The 1974 study reported that grooming was effective in reducing the infection of cattle, but the action of the plant (repellent or toxic) was not known. Further research into different animal diseases conducted in 1995 and from 1996 to 2000 has revealed more research leads. The study conducted by Lans in 2001 revealed that black sage (Cordia curassavica) has been used to control ticks in the Caribbean since the 1800s or before. Other medicinal plants used to control parasites that live inside their host (endoparasites): - kojoroot (Petiveria alliacea), - caraaili (Momordica charantia), - neem (Azadirachta indica), - wild balisier (also called mardi gras) (Renealmia alpinia), - cedar (Cedrela odorata), - congo lala (Eclipta alba), - sweet-broom (Scoparia dulcis). Dried, powdered seeds of Manilkara zapota, Pouteria sapota and Mammea americana are used in cuts and wounds to control parasites that live on the outside of their hosts (ectoparasites) and prevent the infestation with the larvae of flies in animals. The seed paste (with coconut oil) is rubbed on animals to keep away flies and ectoparasites. The discharge from the cut stem of an already harvested banana plant (Musa species) is collected on a piece of cotton, which is then placed in a deep wound to kill the fly larvae that cause myiasis. The exudates-soaked cotton is also used in wounds to prevent infection.