The reduction of the surfaces occupied by the plum trees orchards with a very low yield per 1 ha, occurs in the conditions fruits boot hon the market of Moldova Republic and on the world one. The cause of obtaining of the reduced yields per 1 ha is very varied. This is due to the pests attack among which is the frequent spread species on the entire territory of Moldova republic, named the plum tree wasp – Eurytoma schreineri Schr. The basic methods in the seeds wasp fighting are agro technical and chemical ones. According with the data presented by Gatina (1989), the application of the chemical treatment is effectuated on the appearance of the first females. Some authors indicate that one female can deposit 30-40 eggs, but the number of males is bigger than the females’ one. These contradictory data determined the examination of the relation between the sexes, the real and potential fertility of the females of this species.