Abstract: 【Aim】 This study aims to determine the morphological and biological characteristics of different developmental stages of Thaumantis hainana and to define its host plant. 【Methods】 Female adults of T. hainana were collected from wild habitats and put into triangular paper envelopes for laying eggs. Its larvae were bred with the obtained eggs in an incubator under the conditions of 26℃, 40% relative humidity and 16L∶8D photoperiod with Phoenix loureirii leaves. The morphological characteristics of larvae were observed, and the body length and the width of head capsule of larvae of different instars were recorded. Some morphological characteristics of other developmental stages were also recorded. 【Results】 T. hainana exhibits complete metamorphosis with four developmental stages including egg, larva, pupa and adult. Eggs are round and have a smooth surface. Eggs are about 2.5-2.8 mm in diameter. The larva has 5 instars, and the body length and the width of head capsule of the larva increase gradually with the increase of larval instar. And it has hanging pupa. Adults do not show sexual dimorphism.【Conclusion】 This study primarily clarified the morphological and biological characteristics of different developmental stages of T. hainana， and defined P. loureirii as one of its host plants, enriching the basic data of T. hainana.

Key words: Thaumantis hainana, morphology, biology, host plant, life history, Hainan