: In order to determine the numerical structure of the drifting aquatic insect community and compare it with the structure of the benthic insect community, in a segment of the Santa María river, two sampling stations were selected sampling, where drifting aquatic insects and benthonic insects were collected. The Jaccard similarity index showed a similarity value between the fraction of derivative aquatic insects and the benthic community of insects in the studied section of IJ = 75%. This indicates that most of the taxa move in the drift and that the numerical structure of the fraction derived from aquatic insects is no more than a reflection of the numerical structure of the benthic community of aquatic insects, which makes of the drifting ones a density-dependent phenomenon.