Sticky traps. baited with unmated male or female sugarcane borer moths. Diatraea saccharalis (F.), or with solvent extracts of female abdomens, were used to trap moths in the field to determine which sex was attractive, how age affected attractiveness of a moth. what effect mating had on subsequent attractiveness, the time of day when most sexual activity occurred in nature. and which organic solvents were best for preparing potent extracts of the attractive chemical substance. A potent chemical sex attractant was found in the female moths. Females begin to emit this chemical soon after emergence. and are most attractive during their first 3 days of life, after which attractiveness decreases with age. Females generally cease to attract males after mating has occurred. and most females mate only once in nature. Sexual activity of moths in the field was mostly confined to the hours between 1 and 4 AM. The attractive substance was extracted by crushing abdomens of young virgin female moths in various organic solvents. Abdominal extracts prepared in benzene and methylene chloride were most effective in attracting male moths. The attractive substance was effective for only a few hours when exposed to the environment on filter papers.