How citrus psylla attacks citrus plants?

In plants attacked by citrus psylla we can see young brownish nymphs of psylla crawling on the young flush .Several dirty gray colour adults can be seen sitting in line with tails upwards. Voluminous de-sapping by the nymphs results into the drop of flush, flowers and berries. Affected branches dry and die-back sets in. The nymphs also excrete white crystalline powder, which invites fungal infestation. Psylla can be controlled by spraying acetamiprid 0.2 g/litre water twice with 10 days interval during the initial days of flushing.