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Coffee root mealybugs are a limiting pest in Colombian coffee farming; Puto barberi (Cockerell, 1895) (Hemiptera: Putoidae) is the prevailing species. In order to propose a strategy for the control of this pest, strains of Metarhizium anisopliae Ma 9236 and M. robertsii were evaluated under laboratory conditions at concentrations of 1x107 conidia/mL; mortalities between 80% and 84% on P. barberi were found. They were also evaluated on coffee seedlings infested with the pest in three different trials. In the first one, 4 to 6-month-old plants infested with oviplen P. barberi females treated with 50 cm3 of: 1. M. anisopliae, 2. M. robertsii both at 2x10 10 conidia/L and 3. Water as control. With the water treatment, the infestation percentage was 100% and 25 mealybugs were found per plant. The application of M. anisopliae decreased the mealybugs infestation by 10% and reduced the population by 55%. M. robertsii decreased the infestation by 40% and the insect population by 86%. In trial 2, M. robertsii vs. Water showed results similar to those obtained in trial 1 and 50% plant protection was achieved. In trial 3, the treatments corresponded to: 1. M. robertsii (2x10 10 conidia/L). 2. Azaridachtin 6% water soluble powder (3g/L). 3. Chlorpyrifos 75% WG (3g/L) and 4. Water. In the water control treatment the infestation percentage was 65%, in the other treatments the infestations were between 11 and 22%, which differed from the control, but were statistically similar to each other. M. robertsii is a good candidate to be evaluated under commercial and field seedling conditions