Recently introduced in Senegal, the parasitoid Diadegma insulare (Cresson) quickly acclimatized to the point of occupying the niche of the parasitic procession of the pest Plutella xylostella (L.). This study aims to evaluate the performance of the parasitoid D. insulare as a biological control agent for the diamondback moth. The work was carried out in the laboratory at a temperature of 25°C and a relative humidity of 60%. Ten females of the parasitoid, after 24 hours of mating upon emergence, were each placed in contact with 100 host caterpillars. The latter were removed from the cages 24 hours later and monitored until emergence, at which point the number of parasitized caterpillars was determined. This experiment was repeated throughout the female’s life. The aggressiveness of the females, the parasitism rate, and the influence of the larval stage on parasitism were evaluated. The results showed high aggression in females, which varied significantly with age (93% and 32%). The average parasitism rate was approximately 70%. In 15 days of oviposition, a female D. insulare is capable of parasitizing 809/1500 available caterpillars. Females remain active throughout their lives and their life expectancy was negatively correlated with the parasitism rate. They parasitized more L2 stage caterpillars, but their cycle duration was longer (15.9 days). The sex ratio shows a dominance of males. The parasitoid D. insulare is a good biological control agent and can be a good alternative in integrated pest management.