The lethal and repellent effects of five essential oils were estimated for the first time against the buffalo louse, Haematopinus tuberculatus, and flies infesting water buffaloes in Qalyubia Governorate, Egypt. For the in vitro studies, filter paper contact bioassays were used to test the oils and their lethal activities and compared with that of d- phenothrin. Four minutes post-treatment, the LC50 values obtained were 2.74, 7.28, 12.35, 18.67, and 22.79% for camphor (Cinnamomum camphora), onion (Allium cepa), peppermint (Mentha piperita), chamomile (Matricaria chamomilla), and rosemary oils (Rosmarinus officinalis), respectively, whereas for d- phenothrin, it was 1.17%. The LT50 values were 0.89, 2.75, 15.39, 21.32, 11.60, and 1.94 min post-treatment with 7.5% camphor, onion, peppermint, chamomile, rosemary, and d- phenothrin, respectively. All applied materials, except rosemary, were lethal to the eggs of H. tuberculatus. Despite the results of the in vitro assays, the in vivo treatments revealed that the pediculicidal activity was more pronounced with oils. All treated lice were killed after 0.5- 2 min, whereas with d- phenothrin, 100% mortality was reached only after 120 min. The number of lice infesting buffaloes was significantly reduced 3, 6, 4, 6, and 9 days post-treatment with camphor, peppermint, chamomile, onion, and d- phenothrin, respectively. Moreover, the oils and d- phenothrin significantly repelled flies for 6 and 3 days post-treatment, respectively. No adverse effects were noted on either animals or pour-on operators after exposure to the applied materials. Consequently, some Egyptian essential oils show potential for the development of new, speedy, and safe lousicides and insect repellents for controlling lice and flies which infest water buffaloes.