Integrated Pest Management
Lace Bugs
Corythuca spp.
Adult lace bugs and eggs (David Cappaert, Bugwood.org)
Walnut lace bug nymphs (Whitney Cranshaw, Colorado State University, Bugwood.org)
Lace bug stippling (Jim Baker, North Carolina State University, Bugwood.org)
Pest Description
- adults: tiny, 1/8 – 5/16 inch long; delicate, lacy wings held flat over the back; flat appearance
- nymphs: smaller, typically darker with spines on the body; body is rounded or flattened
- eggs: cylindrical, black and laid in evenly spaced clusters on the undersides of leaves
Host Plants, Diet & Damage
- primarily oak, chokecherry and sycamore in Utah; apple, ash, California lilac, poplar, firethorn, willow
- feed on sap from the undersides of leaves
- cause yellow to white stippling or spots and interveinal necrosis visible on the top of leaf
- damage resembles that of spider mites and leafhoppers
- undersides of leaves appear dirty; adults, nymphs, eggs and shed skins present
- infestations on oak can cause leaf necrosis and leaf drop
- leave black, varnish-like fecal spots on leaf undersides
Biology, Life Cycle & Damaging Life Stage
- overwinter as adults on or near host plants
- fly to expanding host foliage in spring to feed
- adults lay eggs on the undersides of host leaves
- nymphs and adults feed on the undersides of leaves
- two or more generations per year; overlapping life stages present
IPM Recommendations
- Manage trees to improve or maintain health.
- Damage is primarily an aesthetic issue; tolerate pest.
- Apply an insecticide (carbamate; horticultural oil, insecticidal soap, neem oil, neonicitinoid (soil systemic); pyrethroids; spinosad) to the undersides of leaves.