There are many species of lace bugs, some infecting deciduous plants while others infect evergreens. 
Tree Symptoms
Infested leaves will have a whitish flecked damage called stippling. Large populations of lace bugs cause premature leaf drop and weaken plants by removing nutrients from their leaves. To pinpoint lace bug activity, look for blackish, shiny droplets of lace bug excrement on the bottom of the leaf.
A group of baby lace bugs looks like a dark smudge on the leaf, but can be identified with closer observation.
Host Plants
- Deciduous plants: cotoneaster, hawthorn, oak, pyracantha, quince and sycamore
- Evergreen plants: azalea, mountain-laurel, pieris and rhododendron
Treatment and Management
Monitor leaves in late May at three-to-four-week intervals. An insecticide application may be necessary from late may through mid-August. When planting a tree, choose a shady, cooler site where naturally occurring fungal diseases will attack lace bugs and reduce their population.