In a review of the pests and diseases of rice in Vietnam from 1975 onwards, Van Dinh and Doanh (2010) reported 17 key pests of rice. The most important in terms of crop areas damaged were the brown plant hopper Nilaparvata lugens (Stal), the vector of the ragged stunt and grassed stunt viruses, the rice leaf folder Cnaphalocrosis medinalis (Guenee), and the yellow rice stem borer Scirpophaga incertulas (Walker). Among four stem borer species in the Red River Delta, S. incertulas, Chilo suppressalis (Walker), Chilotraea auricilia (Dudgeon) and Sesamia inferens (Walker), S. incertulas was the dominant species, accounting for over 90% of all stem borer populations (Ho et al., 2013). However, during 2010 and 2011, the incidence of S. incertulas at Haiphong Province, a coastal area of Northern Vietnam, was very low (Ho et al., 2013). In northern Vietnam where two rice crops are grown per annum, S. incertulas has six generations per year, two on the first crop and four on the second. C. medinalis has eight overlapping generations per year, seven generations being on rice with one generation on wild grasses. There are two main rice production deltas in Vietnam, i.e., the Red River Delta and the Mekong River Delta, damage caused by S. incertulas being greatest in the former. Large areas of rice are mono–cropped in the deltas. In the Red River Delta the rice fields are sub–divided into numerous small contiguous plots (typically 20–50 plots per ha) each managed by a different farmer. In The Mekong River Delta plots are typically 1–10 ha. In both deltas farmers mainly act independently, and, as a result, the application of control measures is generally uncoordinated, resulting in comparatively poor control of these important pests. Currently, S. incertulas and C. medinalis are controlled with insecticides, one to two spray applications being made on average per crop against each pest, and a wide range of insecticides is used. Sprays to small plots are typically applied with hand lances using knapsack sprayers by individual farmers. The standard of insecticide control is variable and often poor, allowing high populations of the pest in localities to act as a source of infestation for adjacent areas where the pest has previously been well controlled. Better area–wide control tactics for the pests would be beneficial. The female sex pheromone of S. incertulas was originally identified from populations from The Philippines as a 1:3 blend of (Z)–9 hexadecenal and (Z)–11–hexadecenal (Cork et al., 1985). Cork et al. (1985) also found (Z)–11– hexadecen–1–ol and hexadecanal to be produced by females but the former compound reduced catches of (Z)–11–hexadecenyl acetate and (Z)–13–octadecenyl acetate improve the attractiveness of the standard sex pheromone of the yellow rice stem borer Scirpophaga incertulas (Lepidoptera: Pyralidae) in northern Vietnam