Psyllid Pest

Psyllids (superfamily Psylloidea) are tiny 2 to 5 mm sap-sucking insects commonly called jumping plant lice, whose most destructive species — the Asian Citrus Psyllid (Diaphorina citri) — is the primary vector of Huanglongbing (HLB, citrus greening disease), the most devastating citrus disease currently without a cure.

Adults are brownish, hold their clear wings at a characteristic 45-degree roof-like angle when resting, and jump powerfully using enlarged hind legs. Nymphs are flat, yellowish-green, and surrounded by white waxy tubular filaments. Eggs are bright orange, spindle-shaped, and deposited specifically at the tips of new leaf flushes — which is why protecting flush growth with targeted insecticide during spring is the most critical control window.

Psyllid salivary secretions cause leaf curling, distortion, and yellowing of young shoots; the honeydew coats plant surfaces, blocks photosynthesis, and provides a medium for black sooty mould that reduces yield further. The real economic threat comes from pathogen transmission: a single infected adult Diaphorina citri feeding for as little as 30 minutes can transmit Candidatus Liberibacter asiaticus, the HLB bacterium, into a previously healthy tree.

HLB causes blotchy mottle discolouration of leaves, small lopsided fruit with bitter juice, premature drop, and irreversible tree decline — rendering the tree completely unproductive within 3 to 5 years of infection. Beyond citrus, other economically important psyllid species include the Tomato Psyllid (Bactericera cockerelli) attacking tomatoes, potatoes, capsicum, and eggplant; the Pear Psylla (Cacopsylla pyri) damaging pear orchards; and species attacking eucalyptus, olive, pepper tree, and fig.

Psyllid populations peak during spring and early monsoon when vigorous new plant growth provides abundant feeding sites on new flush shoots. Control relies on biological agents — particularly the host-specific parasitic wasp Tamarixia radiata, which is commercially available in India — neem oil at 0.5 percent applied to new flush growth, yellow sticky traps for population monitoring, and systemic neonicotinoids applied as a soil drench for severe infestations, strictly avoiding application during bloom to protect managed pollinators and natural enemies.