Many different species of scale insects trouble gardeners. They get their name from protective scale-like coverings they produce, which are not part of the pest itself. Scale insects fall into two main categories: armored or soft. As the names suggest, armored scales produce a hard covering, while soft scale coverings are waxy and soft. Both types of scales damage plants, from lawn grasses to shrubs and fruits. Like aphids, soft scales excrete a sticky, sweet substance called honeydew, which attracts nuisance ants as well.
Identification: At first glance, many scale insects look like a small, circular bump that's part of the plant. Depending on the species, they vary in color from brown to cottony white and measure up to 1/4 inch long. Scale nymphs are known as crawlers and are similar in appearance. About the size of a pinhead, they're very mobile as they feed. Mature scale insects rarely move once they settle into a spot.
Signs/Damage: Scales feed on plant juices by piercing and sucking plant leaves, stems and fruits. Adults are visible on plants, though they often blend in. As stem and leaf damage progresses, plants turn yellow, twigs die back and whole plants wither and die. Ant-attracting honeydew produced by soft scales often develops black sooty mold.
Control: Effective scale control targets nymphs, before they develop a protective covering, along with mature pests. GardenTech® brand offers several products to kill scale insects by contact and keep protecting for up to three months.
- Sevin® Insect Killer Ready to Use is ideal for target spot treatments of specific plants or small garden areas. The nozzle allows you to select a narrow, direct stream or a wider spray pattern.
- Sevin® Insect Killer Concentrate provides a simple and economical option to treat scale on small trees and shrubs as well as larger lawn and garden areas. Use with a pump-style sprayer, and cover all plant surfaces thoroughly.
- Sevin® Insect Killer Granules target scales at ground level, including species such as “ground pearls" that suck sap from grass roots. Apply the ready-to-use granules with a regular lawn spreader. Then water immediately to release the active ingredients and reach scales above and below the soil line.
Tip: Ants will protect honeydew-producing scale insects from beneficial predator insects that normally help keep scales in check. Maximize scale control by treating nuisance ants as well.
Always read product labels and follow the instructions carefully.
GardenTech is a registered trademark of Gulfstream Home and Garden, Inc.
Sevin is a registered trademark of Tessenderlo Kerley, Inc.
- "Scale insect" by USGS Bee Inventory and Monitoring Lab (public domain)
- "Ants tending scale insects on a leaf" by Scot Nelson licensed under CC BY 2.0
- "Citrus Scale" by Scot Nelson licensed under CC BY 2.0
- "Oystershell scale (Lepidosaphes ulmi) (Linnaeus)" by Whitney Cranshaw at Colorado State University (Bugwood.org) licensed under CC BY 3.0 US
- "Tahitian gardenia: Sooty mold and scale insects" by Scot Nelson licensed under CC BY 2.0