A kairomone from adult Cydia pomonella L. scales is an important factor in the host recognition and searching behaviour process of Trichogramma cacoeciae Mar-chal and Trichogramma dendrolimi Matsumura. The Trichogramma spp. used the chemicals from the host eggs for orientation to host and increased their parasitism. The females of T. cacoeciae*, T. dendrolimi** and T. dendrolimi*** contacted the unwashed host eggs significantly longer than the washed eggs. Washing the codling moth eggs with hexan significantly reduced the parasitism of all the tested Tricho-gramma strains compared to unwashed eggs. The treated apple trees with wing scales of C. pomonella had significant influence on the parasitism compared to un-treated trees. The percentage parasitism of codling moth eggs on the treated trees (31.6%) was significantly higher than on the untreated trees (19.3%).