Extensioneers throughout Ohio have reported high lace bug populations this season. It is speculated these small sucking insects may have benefited from hot, dry conditions that may be coming to an end; for now. The most obvious lace bugs include: basswood lace bug (Gargaphia tiliae), hawthorn lace bug (Corythucha cydoniae), oak lace bug (C. arcuata), and sycamore lace bug (C. incurvata).
These lace bug species live on the undersides of leaves where they use their piercing/sucking mouth parts to suck juices from their host plants. As with all lace bugs (family Tingidae), their feeding produces tiny yellow or whitish leaf spots (stippling) that may coalesce to produce large, yellow-to-copper colored areas on leaves, and early leaf drop. It is not unusual for feeding symptoms of basswood, hawthorn, and oak lace bugs to appear as distinct 1/4 - 1/2" diameter spots on the upper leaf surface. Lace bugs also deposit unsightly hard, tar-like spots of excrement onto the leaf surface as they feed. Most lace bugs have multiple generations per season; their damage builds with each succeeding crop of new bugs.
Basswood lace bugs may be found on all members of the Tilia genus in Ohio; however, they have a particularly affinity for silver linden (T. tomentosa). Oak lace bugs may be found on both red and white oaks. Hawthorn lace bugs feast on wide variety of rosaceous plants as well as a few plants outside of the rose family. They are commonly observed on hawthorn as well as Cotoneaster sp. and Amelanchier sp.
Recent localized heavy rains coupled with high winds in Ohio have impacted some of the bugs, particularly sycamore, hawthorn, and oak lace bugs. However, their stippling damage will remain evident for the rest of the season. Lace bugs that feed on the lower leaf surface can be managed earlier in the season by targeting the undersides of leaves with an appropriately labeled insecticide. Of course, you must read and follow label directions paying particular attention to avoiding impacts on pollinators (e.g. "Bee Friendly" label restrictions).