Technical Abstract: Orchard studies were conducted in 2005 and 2006 in apple and pear to evaluate the larval kairomone (E,Z)-2,4-decadienoate (pear ester) as a formulation additive to improve the efficacy of the granulovirus (CpGV) of the codling moth, Cydia pomonella L. (Lepidoptera: Tortricidae). The addition of a 5% a.i. microencapsulated formulation of pear ester (PE-MEC) had significant but inconsistent results in our tests. In ‘Golden Delicious’, PE-MEC (3.7 g a.i./ha) added to CpGV (2.2 - 6.6 × 1012 granules/ha) significantly reduced overall codling moth fruit injury in the second but not the first larval generation, although no reduction in the numbers of live larvae (dissected from infested fruit or collected in orchard tree bands) was observed. In 2006 apple tests, the addition of PE-MEC (4.7 g a.i./ha) to CpGV (6.6 × 1012 granules/ha) did not reduce fruit injury or increase larval mortality of first generation codling moth in mixed blocks, ‘Golden Delicious’, ‘Fuji’, ‘Gala’ and ‘Delicious’. In studies in ‘Bartlett’ pear in 2005, a low rate of PE-MEC (1.5 g a.i./ha) added to CpGV (1013 granules/ha) caused a moderate reduction in fruit injury at harvest compared with CpGV alone, but no reduction was observed in 2006 when a higher rate of PE-MEC (3.7 g a.i./ha) was tested. However, in the latter tests, the percentage of larval mortality and shallow stings in infested fruit was higher in CpGV + PE-MEC treatments over CpGV alone, which was not observed in 2005. Compared with untreated controls, the PE-MEC formulation alone also reduced fruit injury (mid-season in ‘Bartlett’) and larval survivorship inside infested fruit at harvest (2006 apple tests and both years in ‘Bartlett’).