This week I have gotten three samples from the Plant Disease and Insect Clinic with sycamore lace bug, Corythucha ciliata. I had just taken some pictures of these beautiful critters last week when I was in Asheville. They really do a number on sycamore leaves and this time of year heavily infested sycamores look pretty bad. The other lace bugs that are important landscape pests are the azalea lace bug and hawthorn lace bug. Like these, the sycamore lace bug causes stippling damage by piercing the underside of leaves with its stylet and sucking out the fluids. Large yellow and gray areas develop on the top of the leaves. In some cases, most leaves on a tree can be entirely covered in stippling damage.
Sycamore lace bugs are a native insect. They overwinter as adults under bark or in other sheltered spots and become active soon after bud break. They lay eggs in leaves and complete their lifecycle in around 30 days. However, research from China, where this is an invasive pest, shows that at high temperatures this happens much faster, even twice as fast. This suggests that it could be more abundant in hot urban areas where sycamores are often planted in parking lots and along roads. My experience suggests this is true. Sycamores are wetland trees and probably are not very happy in hot, sunny, dry spots, but lace bugs clearly are.
Management of sycamore lace bugs will be similar as for other lace bugs, but you are typically dealing with large trees instead of small azalea bushes or cotoneaster. Thus systemic insecticides applied as a drench can be a good option. Applications of horticultural oil should also help keep abundance low just by killing adults and nymphs that are present.
Article written by Glenn Palmer, Extension Master Gardener Volunteer.