Abstract: From 2007 to 2009 field observations were carried out in two vineyards (organicallyand conventionally managed) in Menfi (Agrigento province, Sicily). Population dynamics of twoleafhoppers, Jacobiasca lybica (cotton leafhopper) and Zygina rhamni were followed bychromotropic traps and leaf observation in field. Both species were constantly present invineyards. Z. rhamni did not register statistical differences between the two fields, while J. lybicawas mostly present in the conventionally managed field. In this last vineyard for two consecutiveyears (2007 and 2008) J. lybica population exceeded the intervention threshold of 0.5leafhopper/leaf. On the other hand, in the organically managed vineyard the cotton leafhopperpopulation remained below the intervention threshold for all the observation period.