Azalea lace bugs are rather small insects, but their feeding habits leave telltale signs on the foliage. The leaves will have a whitish cast to them. Close examination will reveal very fine specks on the upper leaf surface where the green pigment, chlorophyll, is absent. If you look on the underside of the leaves, you will see tiny tar‑like spots of excrement. High populations of lace bugs are more prevalent on plants located in full sun.
Adult lace bugs are less than one‑quarter of an inch long. They have a black body and clear wings with darker markings that are lacy in appearance. An adult also has an odd crystal-helmet-like structure over their head. The immature lace bugs do not have wings, are smaller than the adults, and have black, spiny projections all over their bodies. Adult females insert spindle‑shaped white eggs just under the lower leaf surface and cover with excrement.
All feeding activity occurs on the undersides of leaves. The insects have piercing‑sucking mouthparts that remove the contents of plant cells. There are up to four generations per year, and lace bugs survive the winter as eggs within the previous season’s leaves.
Control consists of insecticide treatments (both synthetic or organic) several times during the year. The eggs hatch when new growth begins during the spring. This is usually in late April to early May. Treatment at this time will greatly reduce the succeeding generations. Reproduction can continue through September, so insecticides should be applied if you see a resurgence in the insects.
For control recommendations, see HGIC 2051, Azalea & Rhododendron Insect Pests. Always read and follow label directions when using any pesticide.