**Sycamore Lace Bugs** (*Corythucha ciliata*) are minute, sap-sucking insects that specialize in attacking the foliage of **Sycamore** (*Platanus* species), and occasionally related ornamental trees. They are named for their exquisite, lace-like wing structure. The conflict is severe aesthetic damage: they feed exclusively on the underside of the leaves, causing the upper surface to become **stippled with tiny yellow or white spots** and then turn a distinctive, unsightly **bleached or bronzed color** in early summer, leading to premature leaf drop.
Taxonomy and Classification
Sycamore Lace Bugs belong to the order Hemiptera (True Bugs). They undergo simple metamorphosis. They have multiple generations per year, which allows populations to build rapidly and cause severe aesthetic damage by mid-summer. They overwinter as adults, tucked into bark crevices on the host tree.
Physical Description
Adult Lace Bugs are minute, 1/8 inch long.
- **Appearance (Key ID):** Small, flattened body with unique, highly sculptured, transparent **lace-like wings** covering the body.
- **Habitat (Key ID):** Found exclusively on the **underside** of sycamore leaves.
- **Damage Sign (Key ID):**
- **Stippling:** Tiny white or yellow dots (stippling) on the upper leaf surface.
- **Bronzing:** Leaves turn a uniform, dull bronze, yellow, or bleached white color by July/August.
- **Tarsal Spots/Residue:** Dark, sticky droplets (excrement) and shed skins visible on the leaf undersides.
- **Conflict:** Severe aesthetic damage and nuisance.
Distribution and Habitat
Sycamore Lace Bugs are found wherever sycamore and plane trees are grown in North America and Europe. Their habitat is the undersides of the host tree’s leaves.
Behavior and Conflict
The conflict is predominantly visual and nuisance.
- **Aesthetic Loss:** The premature bronzing of the leaves ruins the ornamental value of the tree and can stress the tree by forcing premature defoliation.
- **Human Nuisance:** When populations are high, the lace bugs often drop or fly off the leaves and bite people using the outdoor area beneath the tree. The bite is irritating but not harmful.
- **Stress:** Although healthy mature trees usually survive, heavy, repeated feeding can contribute to dieback, especially when combined with drought stress.
Management and Prevention
Control is integrated pest management (IPM), targeting the early generations.
- Use a strong jet of water to wash the insects off the underside of the leaves. This must be done repeatedly early in the season to disrupt the first generation.
- **Systemic Treatment:** For high-value trees, apply a systemic soil drench or trunk injection in the spring to provide season-long control, killing the insects as they feed.
- **Contact Spray:** Apply insecticidal soap or horticultural oil to the **underside of the leaves** in the late spring when the first generation nymphs are active. Complete coverage is essential.
- Ensure the tree is adequately watered and fertilized to minimize stress and maximize its ability to tolerate the damage.
Conservation and Research
Sycamore Lace Bugs are managed as aesthetic landscape pests. Research focuses on their overwintering behavior in bark crevices and the efficacy of systemic pesticides in urban settings.