The objective of this work was to determine the horizontal and vertical distributions of cocoons of Nematus desantisi Smith, in soils with plantations of clones of Salix sp. Samples were taken in two places, in areas that had suffered attacks in the previous spring and summer. Special soil bores were used to detect cocoons and an analysis of variance and Tukey's range tests were done. Exponential patterns were adjusted and plotted in order to detect general tendencies in horizontal and vertical distributions: Y = a + exp (b + cX), where: X (independent variable) = distance to the tree (m) or depth of the sample (cm); Y (dependent variable) = number of cocoons. The horizontal distance of the tree sample was found to be the determinant variable. N. desantisi cocoons were found at the bottom of the trees, at distances that may be influenced by the environment. N. desantisi cocoons were discovered at depths of up to 6 cm, but were mainly distributed in the upper 3 cm of the soil.