The avocado lace bug (Pseudacysta perseae) is a pest that has become increasingly significant to avocado plants since the early 1990s. The avocado (Persea americana) is the main host for this pest in Southern coastal Florida. The avocado lace bug does damage to avocado leaves with its piercing-sucking mouthparts. This pest attacks the underside of the leaves where it feeds by extracting chlorophyll and other plant fluids. This causes destruction of plant cells and leads to the chlorotic and necrotic damage you see in the photos below. When looking at a tree with this pest you may observe leaves that look brown and “scorched”.
The avocado lace bug is a very small pest- only about 2mm as an adult. This can make it difficult to see the insect, but you can see them on the photo of the underside of the leaf- they look like little black specks. It may be easier to see them using a hand lens or you can shake an infested branch over a sheet of white paper. They will be easier to spot and identify on the paper than on the leaf. Here is a close-up of the avocado lace bug:
The adults are the larger ones with the “lacy” wings on the left and the nymphs are the smaller black insects on the right. The black oily-looking specks are the eggs.
If there is a large infestation of avocado lace bugs it may result in some defoliation, and the resulting damage from the pest can become an opening for the introduction of infections. If you discover that your avocado has this pest there are a few controls at your disposal. A strong jet of water will dislodge them from the plant, but may not kill them. This is probably most effective if the infestation is minor. Insecticidal soaps or horticultural oils are effective controls if they are applied directly to the insects. Monitoring for this pest in the future will be necessary and the treatment will need to be repeated as necessary according to the label. Of course, the mechanical control using the jet of water can be used anytime.
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