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Diaphanes lutescens was originally described by Walker, 1858, using specimens from Sri Lanka. The systematics and biology of this species has been unexplored since it was first described in the early eighteenth century. This paper provides a detailed description of systematics and biology of the identified male, female and larvae of D. lutescens with their areas of incidence and habitat types in Sri Lanka. Females and larvae were identified when they were associating with males in the same habitat. Remarks of their flashing patterns and flying behaviour are addressed.