The citrus psylla causes raised, pock-like swellings on the upper surfaces of young leaves. For each swelling there is a corresponding pit or hollow on the underside of the leaf – this is where the nymph stage of the psylla will have fed. This problem normally occurs on citrus and related indigenous trees, such as Cussonia spicata (cabbage tree). Predatory wildlife, like ladybirds, wasps, lacewings and birds and spiders, can help to control the pysllid population. Control of ants by the gardener can also help.
Unless the infestation is severe, neither the fruit nor the general health of the affected tree should suffer. Organic insecticides that contain natural pyrethrins can be used to combat severe infestations, but they will unfortunately also kill most of the psylla’s natural enemies (as would any non-organic insecticide).
Products on the market:
Controlling Citrus Psylla:
Makhro Agro Koinor
Kirchhoff’s Ludwig’s Insect Spray+
Kirchhoff’s Margaret Roberts Organic Insecticide