In this study, larval stages of Citrus leafminer, Phyllocnistis citrella Stainton (Lepidoptera: Gracillariidae), which Citrostichus phyllocnistoides Narayanan (Hymenoptera: Eulophidae) prefers for parasitization and its functional and numerical responses were studied in 2008-2009. The larval stage preference studies were conducted in conditions with I., II. and III. larval stages of the pest together and each larval stages seperately in the cages. Determination of functional response was studied with mated one day old female parasitoids with 5, 10, 15, 20, 25, 30, 35 and 40 P. citrella larvae density. In numerical response studies, 2, 4, 6, 8, 10 ve 12 individuals of mated one day old C. phyllocnistoides females were released to potted seedlings which had 30 P. citrella larvae on it. It was conducted that C. phyllocnistoides mostly preferred the Ill, larval stage for egg laying both all P. citrella larval stages seperate or together. In reply to increasing host population density, the number of eggs laid by parasitoid increased parallel to increasing host density until 30 host individuals. The speed of the laying egg became slower over this level. It was determined that the parasitoid demonstrated a Holling type II functional response to increasing host density. According to Holling's disk equation, searching rate (a) and the handling time (Th) coefficients of the parasitoid were 0.571 h(-1) and 0.0997 h, respectively. In numerical response studies, the maximum parasitization was determined at six parasitoid density with 16.53 +/- 0.22 individuals.