Field trapping tests with various blends of the synthetic compounds dispensed from high-density polyethylene tubes showed that (E)-2-hexenyl butyrate and (E)-4-oxo-2-hexenal were essential for attraction of male A. spinolae, and catches with a wide range of ratios of these two compounds did not differ significantly. However, adding hexyl butyrate at 50 % or more of the (E)-2-hexenyl butyrate to the binary blend strongly inhibited attraction of males