Eleven species of native or naturalized grasses were found hosting spittlebug nymphs in the natural grassland areas around Brasília in the Fe-deral District of Brazil. A large number of nymphs were found on the species Axonopus marginatus (Trin.) Chase. Out of a total of 224 observed nymphs, 85.7% were found feeding on A. marginatus. Apparently the presence of the spittlebug nymphs in the cerrado vegetation, the Brazilian savanna, was associated with any form of disturbance, such as cattle grazing and partial deforestation. Nymphs were found only in disturbed areas of the "cerrado campo sujo" and in the cerrado sensu strictu. The densities of spittlebug nymphs in the cerrado were lower than the density found in the cultivated pasture. The nymphal density in the cerrado sensu strictu was approximately 105 times lower than the densities in Brachiaria ruziziensis Germain & Evrard area. In two sites of "campo sujo" form of cerrado the densities were, approximately, 2,273 and 1,212 times lower than the densities in B. ruziziensis areas. The distribution and density of the spittlebug in the natural vegetation were influenced by the presence of adjacent infested areas of cultivated pasture. This fact indicates that areas of Brachiaria are the source of infestation for other host plants.
Insecta; nymphal density; Brazilian savanna; Brachiaria spp
