Juvenile Salix alba plants and the parts of older trees with a thin bark are highly affected by Helicomyia saliciperda Duf. (Diptera, fam. Cecidomyidae). The pest is causing galls, which often spread throughout the circumference. This causes the dying of the plant parts above the gall. The damage is particularly significant in the nurseries and younger plantations. For this reason, the pest should be controlled. First experiments dealing with the possibility of the silicon and "Fitobalsam" utilization in the repressive control were conducted in 2003. The research is aimed at finding out the effective protection by the application of silicon and "Fitobalsam", in course of preventing the swarming, i.e. the emergence of adults from the xylem and cortical tissue, as well as to prevent the new egg-laying and larval tunneling in the bark. The experiment was established in the field by the method and extent that enables the statistical processing (ANOVA). The results show that in the treated plants, the swarming of adults was statistically significantly lower compared to untreated plants. The first results indicate that the initial research should be continued, and especially in the direction of identifying the width of the zone around the gall that should be treated, as well as the rate of healing of the damaged tissue.