The float system is a well-known method to obtain the best tobacco seedlings. The seedlings absorb nutrients from a liquid fertilizer dissolved in the basin water, harmonized specially for tobacco to get uniformly growing and robust seedlings. Pest control is carried out using different chemical products and methods according to the expected pests. The covering of the float system is conventionally carried out using a plastic cover to create a greenhouse effect, as well as colored plastic covers to prevent sun baking and to produce stronger seedlings due to the slower growth. The purpose of this study was to evaluate the effect of a special polypropylene non-woven cover sheet on the associated insect fauna in the float system. The field studies were carried out in farm areas in southern Brazil, from 2001 to 2004 crops. Insects were collected inside the Float System tunnel using yellow trays during the tobacco seedlings growing and maturing period, aiming to improve the knowledge about the associated entomological fauna. Three different treatments were used to verify the incidence of insects inside the Float System: with polypropylene non-woven coversheet, without polypropylene non-woven coversheet and outside the float system. More than 10.000 individuals were collected, belonging to five insect orders: Diptera, Hymenoptera, Hemiptera, Coleoptera and Orthoptera ( Ensifera and Caelifera ). Eighteen of the 41 identified families belong to the order Diptera , while 14 families and one superfamily belong to Hymenoptera. The numbers of individuals in the majority of the orders/families were reduced considerably using the polypropylene non-woven cover, such as Hemiptera / Aphididae and Diptera / Dolichopodidae . This reduction of insect individuals enhanced the transplanting effectiveness due to less immature nymph insect period introduced into the field. The introduction of a polypropylene non-woven cover on the Float System can be considered an effective alternative to reduce the number of insects, as well as reduce the quantity of insecticides used, resulting as an important IPM-Integrated Pest Management tool.