The objective of the present work was to evaluate the conditions of establishment and the adaptation of Ibalia leucospoides (Hockenwarth) endoparasite of Sirex noctilio F., on Pinus taeda (L.) and Pinus patula (Cham. et Schlecht) plantations in Jujuy province. The research was carried out during the 1997-2002 period, in a forest private estate located in La Almona, San Antonio department, Jujuy, Argentina. Larvae and adult couples of I. leucospoides were introduced after and adaptation period in laboratory conditions, were liberated in plantations. From the analysis of results, we can assert that it was possible to settle down, in satisfactory conditions, populations of endoparasite I. leucospoides [ABSTRACT FROM AUTHOR]