Neodiprion sertifer is a primary insect that causes significant damage to the pine forests in the Lakes District. All aspects of this insect should be understood well to control this species, its biology should be identified under natural conditions and its natural enemies should be identified to perform biological control. Therefore, the biology of this insect was studied under the field conditions in the forests of the Lakes Region, which was our study site, where the insect caused damage and frequent epidemics, its natural enemies that were effective on the population were identified. It was found that these insects passed the winter as eggs, while the larvae hatched in late March and early April. The young larvae were observed to feed first on the leaves up to the middle nervous parts. Starting from mid-May, pupae came out between the needles and in the soil, the adults started flying in late September and until early December. These insects were found to have a wide distribution in the brutian pine plantation site and have one generation each year. Throughout the study, it was observed that the predatory species which was Troilus luridus (Fabricius, 1775) (Hemiptera, Pentatomidae) fed with the larvae of N. sertifer. Neochrysocharis formosa (Westwood 1833) (Hymenoptera; Eulophidae) and Dipriocampe diprioni (Ferriere 1935) (Hymenoptera; Tetracampidae), as egg parasitoids, and Lamachus eques (Hartig, 1838) Agrothereutes adustus (Gravenhorst, 1829), Exenterus amictorius (Panzer, 1801) (Hymenoptera, Ichneumonidae), Brachymeria sp. (Hymenoptera, Chalcidiae), Apanteles sp. (Hymenoptera; Braconidae), Mesopolobus mediterraneus (Mayr, 1903) (Hymenoptera; Pteromalidae) Drino inconspicua (Meigen, 1830) (Diptera, Tachinidae) as larval and pupa parasitoids were observed. Parasitoid species N. formosa, D. diprioni, Brachymeria sp., Apanteles sp. and M. mediterraneus were recorded for the first time in our country as the natural enemies of the harmful insects. Keywords: Neodiprion sertifer, Biology, Natural enemy, Lake’s District