Habitat survey of leaf insect Phyllium westwoodiiWood-Mason was conducted in Mae Tha and Thung Hua Chang districts, Lamphun province. Habitat of P. westwoodii was dry dipterocarp forest with the height of 500-600 meters above mean sea level. In the survey of host plants of P. westwoodii, the total of 12 species in 8 families of plant were found. The host plants were 1) Family Anacardiaceae: Mango, MangiferaindicaL. and Burmese Lacquer, Gluta usitata(Wall.) Ding Hou; 2) Family Burseraceae: Makok kluean, Canarium subulatum Guill.; 3) Family Dipterocarpaceae: Taengwood, Shorea obtusa Wall.; Burmese sal, Shorea siamensis Miq.; Yang-Na, Dipterocarpus alatus Roxb. and Yang Hiang, Dipterocarpus obtusifolius Teijsm. ex Miq.; 4) Family Fagaceae:Ko-Paen, Castanopsis diversifolia (Kurz.) King; 5) Family Irvingiaceae: Wild almond, Irvingia malayana Oliv. ex A. Benn.; 6) Family Meliaceae: Kat lin, Walsura trichostemon Miq.; 7) Family Papilionoideae: Burma Padauk, Pterocarpusmacrocarpus Kurz and 8) Family Sapindaceae: Longan, Dimocarpus longan Lour.The biology of P. westwoodii was studied in the laboratory. The results revealed that P. westwoodii had a long life cycle.During the growth and development of P. westwoodii, some interesting behaviors were observed such as camouflage, mating, egg laying, etc. The information of biology of P. westwoodii and its behaviors was essentially useful for the conservation ofP. westwoodii in the nature.