Direct seeding mulch-based systems of cultivated crops under a pre-established caver crop as millet is a common cultural practice in some areas in Brazil. Lepidoptera pests that damage cotton, soybean or maize, are able to grow in these caver crops resulting in preventive chemical treatments. Few observations are generally available on these pests on caver crops. This work presents the caterpillar dynamics of 5podoptera frugiperda, 5. eridania, Macis latipes and Diatraea saccharalis observed at Primavera do Leste, State of Mato Grosso, Brazil, during the cropping seasons of 2005/2006 and 2006/2007 on four caver crops: Eleusine coracana, millet (Pennisetum), sorghum and Brachiaria ruziziensis. Counting was done with a 1 m2 wooden frame, th rough visual observations of the plants. Rearing of caterpillars was done for the identification of species and parasitoids obtained. A higher number of 5. frugiperda was observed in the millet in 2005, with a maximum of 37 caterpillars per m2 • On sorghum we found 30 caterpillars/m2 or 0.83 caterpillars/plant. Diatraea as a borer attacks the sorghum later than the others pests. M. latipes was also observed in millet. Desiccating the millet at least one month before sowing of the cotton plants is a necessary measure in order to avoid attacks from 5. frugiperda on young plants which can lead to significant resowing. Discussion is made regarding the comparative methodological aspects.