Psyllids (Hemiptera: Psylloidea) are important pests of agricultural crops worldwide. These insects may cause damage to plants by direct feeding and/or vectoring plant pathogens. Psyllid-transmitted bacterial diseases are increasingly becoming important in perennial and annual crops. Several reports have shown that the fastidious bacterium ‘Candidatus Liberibacter’, vectored by at least four psyllid species, is associated with newly-emerging and economically important diseases of crops, including Huanglongbing or citrus greening disease in Citrus spp. and zebra chip in potatoes, Solanum tuberosum L. Huanglongbing is vectored by the Asian citrus psyllid, Diaphorina citri Kumayama, and the African citrus psyllid, Trioza erytreae Del Guercio, whereas zebra chip is vectored by the potato/tomato psyllid, Bactericera cockerelli Sulc Recently, ‘Ca. Liberibacter’ has been associated for the first time with the carrot psyllid, Trioza apicalis Förster, and carrot, Daucus carota L. subsp. sativus, plants affected by this insect in northern Europe. An overview of psyllid species vectoring bacterial diseases to annual crops, with emphasis on potato psyllid and carrot psyllid, is presented herein.