This research was carried out in the Purace municipality, Cauca, Colombia. Its target was to evaluate the insecticide effect of the Bocconia frutescens extract on the white grubs of Ancognatha vulgaris . A randomnized block design with five treatments and three replicates was applied. The treatments T1, T2 and T3 corresponding to 14, 17 and 20% concentrations of the plant extract, T4 to a commercial product (Carbofuran) and T5 as an absolute control. The variables evaluated were the presence of healthy and affected larvae; and the damage percentage on plants evaluated as incidence and severity. Significative differences were found for the % intensity, %infestation, healthy and affected larvae variables, at different evaluated times. The best insecticide effect treatment was T2 (17% plant extract) followed by T3 and T1. For the plant damage variables, the higher percentage treatments were T2 and T5 with 57% intensity and 55% and 45% infestation for T2 and T3 respectively. The presence of alkaloids, terpenes, anthrones and coumarines in the plant extract was demonstrated by phytochemical analysis. The effect of the B. frutescens extract on white grubs was dehydration and flaccidity provoking death at any of the concentrations assayed. This was attributed to the action of single metabolites or their combination.