A single distinct EAG-active compound was found in the extract of virgin females of the sweetpotato vine borer moth, Omphisa anastomosalis (Guenée) (Lepidoptera: Crambidae), and was identified as (10E,14E)-10,14-hexadecadienal (E10E14-16:Ald) at ca. 20 ng/female. Minor related compounds were also identified as hexadecanal (16:Ald), (10E)-10-hexadecenal (E10-16:Ald) and (14E)-14-hexadecenal (E14-16:Ald) at 3.1%, 3.0% and 0.7% amounts relative to the EAG-active component, respectively. In the field, more male moths were captured with traps baited with high amounts of E10E14-16:Ald, which confirmed that this compound is a sex pheromone component. The attractiveness was, however, significantly inferior to that of virgin females. The attractiveness did not increase when minor related compounds were added to the compound. Nevertheless, synthetic E10E14-16:Ald should be useful for monitoring field populations of O. anastomosalis.