Check Now for Hatching Lace Bugs
Steven Frank, NC State University Associate Professor and Extension Specialist Entomology and Plant Pathology, offers this glimpse into a current landscape pest.
There are over a dozen species of lace bugs in NC. The most common species on azaleas drives everyone nuts. Azalea lace bugs (Stephanitis pyrioides) are one of the most damaging pest of evergreen azaleas. They overwinter as eggs inserted into leaves along the midline of azalea leaves and are hatching now. Other common lace bugs are hawthorn lace bug, oak lace bug and sycamore lace bug. Hawthorn lace bugs feed on many common plants including hawthorn, cotoneaster, pyracantha, crab apple, serviceberry (Amelanchier), mountain ash and others.
Lace bugs all cause stippling damage which looks like hundreds of tiny discolored specks on the leaves. Lace bugs feed by poking their needle-like mouth parts into the leaf and sucking out the plant juices, including chlorophyll. Without the chlorophyll, the feeding spots turn yellow or white and eventually brown. Lace bugs also make a lot of fecal spots on the undersides of leaves.
Lace bugs are very predictable and easy to find. They typically occur on the same plants year after year due to their lifecycle. Thus, if a plant had azalea lace bugs last year it will certainly have them this year. Likewise, hawthorn lace bugs overwinter as eggs in leaves or as adults in leaf litter or other sheltered locations near the plant. Hawthorn lace bugs are also strong fliers that can easily travel to new host plants.
Insecticides should be applied when eggs hatch and nymphs appear in spring. Control is best targeted early in the season when nymphs are present for two reasons. First, nymphs are easier to kill than adults and if you kill nymphs before they mature and lay eggs, you have a better chance of clearing up the infestation. Second, the longer azalea lace bugs are on your plant the more damage they do. On evergreen azaleas, this damage sticks around for a long time so plants may be permanently damaged. Scout your azaleas and get those lace bugs cleared up before damage occurs.
A good control tactic is not to plant azaleas in full sun (or next to HVAC units) where it is too warm and where natural enemies like green lacewings, spiders, and minute pirate bugs are rare. Lace bugs are hard to manage with foliar insecticides because they reside on the bottom side of leaves. Be to cover these parts with the horticultural oil or soap or other product you apply. Lace bugs can also be managed with systemic products. However, many of the lace bugs’ favorite plants also have numerous flowers a lot so be conscious of the labels and restrictions regarding pollinators.
Check your plants now just by flipping leaves over to look for tiny new nymphs. For more information, see our Entomology Insect Notes publication on Lace Bugs.