Psylla (from the Greek psulla, meaning flea) is a genus of sap-sucking insects belonging to the order Hemiptera. Twelve species are within the genus, each with a specific host. Some harmful species commonly known as flies belong to neighbouring genera, such as Cacopsylla (which includes most of the pyslla harmful to fruit trees), the Albizia fly (Acizzia jamatonica, from the Psyllidae family) and the laurel fly (Trioza alacris).