A network was created in France to obtain data on the seasonal activity of the psyllid Cacopsylla pruni, vector of European stone fruit yellows phytoplasma. C. pruni was collected on Prunus plants by beating trays. The insect was found in every prospected area. The reimmigrants (adults that have overwintered) were found on Prunus from February to May and the new generation from May to June. Not any C. pruni was found on Prunus after July. Prunus spinosa appeared the preferred host plant compared to the other monitored Prunus. The data are discussed in relation to the control of the phytoplasma disease.