The braconid Mirax insularis Muesebeck Is a koinoboint parasitoid of the coffee leafminer, Leucoptera coffeella Guérin-Méneville & Perrottet, in Puerto Rico. However, their reproductive capacity under artificial rearing conditions of the leafminer is not known. The objective of this study was to determine its reproductive potential in larvae of 1st and 2nd instar of L. coffeella. Reproductive capacity tests showed significant differences (test t-Student, P < 0.05) in the preference of M. insularis for 2nd instar larvae with 7% of parasitization, whereas in 1st instar it gained only 5%. The average oviposition of M. insularis increases three folds (14 eggs per female) in a period of 48 hours on 2nd instar when compared to 1st instar. In the analysis of variance, the treatments that showed a significant difference (Tukey test, P < 0.05) were those with densities of 60 to 80 parasitoids per experimental unit on 2nd instar. Correlation tests find that there is a correlation (R = 0.453, P = 0.547) among the progeny of M. insularis produced when using larvae of the 1st instar. However, there is a positive correlation (R = 0.981, P = 0.019) when using 2nd instar larvae. The parasitization of M. insularis is higher when performing inoculations with 60 to 80 parasitoids on 2nd instar, producing a progeny of 365 and 480 parasitoids, respectively.