Pheromone production of Rhabdoscelus obscurus (Boisduval) was studied in the laboratory. Males and females showed a strong attraction to water and fermented sugarcane and did not release any attractant unless they had fed on sugarcane. The male needed only 15 minutes of contact to produce a pheromone to attract the female, but it needed 24 hours to attract another male. (Attraction between males may be attributed to fermentation products resulting from microbial activities on sugarcane.) Females attracted males after 24 hours of contact with sugarcane, but they did not attract other females. The site of pheromone production was likely in the male hind gut. Extracts from the male abdomen, hind gut, and fecal material were attractive to females. Extract from the whole female body was slightly attractive to males, but none of the parts showed any attraction. Virgin males, 4 to 6 days old, with a cane piece, produced a pheromone which attracted only females. However, the pheromone produced from the same males at the age of 12 to 16 days attracted both sexes. The synthetic pheromone of male boll weevil, Anthonomus grandis Boheman, was attractive to the female of R. obscurus . Field results indicated that R. obscurus responded more strongly to mature males than to virgin males.