Louseflies were found on banteng, hog deer, barking deer and sambar deer at Chiang Mai Nature Education Center. Male and female flies were caged and allowed to feed on banteng (Bos banteng birmanicus Lydekker). Louseflies sucked blood during the night more than during the day. The sucking period averaged 12 minutes. Copulation occurred between 10.00 and 13.00 hours and lasted an average of 48 minutes. After copulation eggs and larvae developed in the uterus for an average of 8.65 days, The louseflies were viviparous and laid a puparium containing the last larval instar which then changed into a pupa. Adults emerged an average of 24.68 days after the puparium was laid. The mean adult longevity was 8.90 and 21.35 days for the male and female respectively. The external and internal morphology of the adult, the development of eggs, larvae and pupae were studied.