Resumo. Os agroecossistemas contem vários agentes de controle biológico atuando simultaneamente sobre diferentes ou o mesmo inseto alvo. A cultura do algodoeiro apresenta um rico complexo de inimigos naturais associados às pragas, dentre eles, destaca-se o predador Chrysoperla externa (Hagen) Compatibility Metarhizium anisopliae (Metschnikoff) Sorokin (Hypocreales: Clavicipitaceae) with Chrysoperla externa (Hagen) (Neuroptera: Chrysopidae)Abstract. The ecoagrossistemas several biological control agents acting simultane ously on different or the same target insect. The culture of cotton presents a rich complex of natural enemies associated with pests, among which stands out the predator Chrysoperla externa (Hagen) and the entomopathogenic fungus Metarhizium anisopliae (Metschnikoff) Sorokin. The objective of this study was to evaluate the compatibility of the fungus M. anisopliae on the biological aspects of the predator C. externa. The first study evaluated the development of C. externa when treated with the following suspensions of M. anisopliae: T1 water (control); T2-10 5 conídios.mL -1 de M. anisopliae (M.a.); T3-10 6 conídios.mL -1 de M.a.; T4-10 7 conídios.mL -1 de M.a.;T5-10 8 conídios.mL -1 de M.a.. The second assay measured the duration of the larval and pupal predator and larval mortality in each treatment. For this, C. externa eggs were individualized in Petri dishes and kept under laboratory conditions. When the larvae of C. externa hatched, whitefly nymphs were offered on leaf discs coming from cotton treated with: T1-water (control); T2 -10 5 conídios.