none There has been continued the adding of the Gypsy Moth's eggs, as an original method of biological control on larger areas of two forests. The data obtained after 8 years' investigation concerning the degree of parasitising Gypsy Moth's young caterpillars by the wasps Cotesia melanoscelus and Glyptapanteles porthetriae , tachinids and partly by diseases, have shown a considerable reductional influence. The useful influence of the adding of Gypsy Moth's eggs in two timings on the synchronization of the presence of corresponding degrees of Gypsy Moth caterpillars and parasites as well as on the entire complex of biotic mortality factors, was confirmed.