Technical Abstract: Codling moths are attracted to acetic acid, and to ethyl-(E,Z)-2,4-decadienoate, the pear ester. Acetic acid is a product of microbial fermentation of sugars, and ethyl (E,Z)-decadienoate is an odorant of pear, which is a host of codling moth larvae. Many more male and female codlling moths were attracted, or were captured in traps, when the compounds were presented together, compared with the chemicals tested separately. This enhancement or synergy of attraction occurred in a flight tunnel study and in three field experiments. The field experiments involved three trap designs, and were conducted in Washington, U.S.A. and in Lincoln, South Island, New Zealand. Given that codling moth attractionto acetic acid is thought to be a food finding behaviror, and ethyl-(E,Z)-2,4-decadienoate is a host odorant (pear), the heightened response to the combined blend supports the hypothesis that codling moths orient to ripe pear odor in search of food, and suggests that some of the reported codling moth orientation to the pear ester is a food finding behavior. The discovery of this attraction synergy provides a stronger lure for female codling moths than currently exists with pear ester alone, and has potential for use in managing this pest of pome fruits and walnuts throughout the world.