The objective of this work was to evaluate the fluctuation and population density of different families of insects by means of attractive food based on oleoresins and sugars in an area under soybean-oat succession. The experiment was carried out in the municipality of Cruz Alta, RS, according to Koppen type Cfa. During the months of March to September, 9 traps were installed with the alimentary attraction around an area of 10.5 hectares, the samplings in the traps were realized every two weeks, being the number of insects belonging to each family accounted for and used for data analysis. The families identified were Curculionidae, Scarabaeidae, Coccinellidae, Noctuidae, Apidae, Chrysomelidae, Syrphidae, Tenebrionidae, Chrysopidae and Pentatomidae. Among the most populous are: Curculionidae, Scarabaeidae and Noctuidae. The Bootstrap estimators (10.75), Jackknife 1 (10.07) and Chao 2 (9.44) indicated proximity between the number of families observed (10) and estimated only for the Jackknife 2 estimator (13.95), there were more families. The soybean-oat succession provides a population increase of herbivores to the detriment of natural enemies. Food-attractive traps based on oleoresins and sugars serve to monitor local entomofauna in areas of soybeans and oats in succession.