Psyllids

Psyllids are small, sap-sucking insects in the superfamily Psylloidea within the order Hemiptera. They are commonly called jumping plant lice and are found in warm, humid regions worldwide. Adults are usually minute and may be winged or wingless; nymphs are more or less stationary on the host plant and often produce waxy secretions or protective coverings called lerps in some species.

The life cycle consists of eggs laid on the aerial parts of host plants, followed by immature nymphs that feed on phloem tissue and pass through several instars before maturing into winged or wingless adults. Eggs and nymphs are typically plant-specific, and many psyllids exhibit strong host specialization or alternate-host life cycles, linking them to particular plant species or families.

Psyllids range from minor to major agricultural pests. They can cause symptoms such as leaf curling, chlorosis, and stunted growth, largely through feeding and the honeydew excreted by nymphs, which can foster sooty mold. Several species are notable disease vectors; for example, the Asian citrus psyllid (Diaphorina citri) transmits the bacterium Candidatus Liberibacter spp., associated with Huanglongbing (citrus greening). The potato psyllid (Bactericera cockerelli) is linked to zebra chip disease in solanaceous crops. Not all psyllids transmit diseases, but their feeding can still cause significant yield losses.

Management of psyllids typically relies on integrated pest management, including regular monitoring and biological control by parasitoid wasps (for example, Tamarixia radiata for citrus psyllids), predators, and, when necessary, selective insecticides. Cultural practices such as removing severely infested plant material and restricting movement of infested stock can also help limit spread.