Should I scrape scales off my plants?
Written by
Liu Xiaohui
Reviewed by
Prof. Martin Thorne, Ph.D.To extract scale bugs from a plant, you will need to exercise a little care to avoid damage to the plant. I only recommend this if you are dealing with a significant infestation where you can see the scales grouped. You will need a soft toothbrush that is soaked in soapy water. Gently wipe and shake the adults off the leaves. Although this will take off the adult scales, you will not be able to get rid of the eggs underneath or crawlers elsewhere on the plant.
Preparation Steps
- Choose soft-bristled brushes to prevent bark damage
- Mix mild soap solution (1 teaspoon per quart)
- Place drop cloth to collect fallen scales
Scraping Technique
- Work in small sections with gentle circular motions
- Angle brush to lift scales without gouging bark
- Focus on main stems where scales cluster thickly
Post-Scraping Care
- Rinse area with clean water to remove soap residue
- Apply horticultural oil to smother remaining eggs
- Dispose debris in sealed bags not compost
The ideal time for scraping is during the dormant seasons when the plants are still quite resilient. I usually scrape in late winter, just before the buds break, and I apply horticultural oil afterward. The horticultural oil helps smother any remaining eggs on the newly scraped surface. For summer infections, I only use fingernails on trees with thick bark and avoid making the exhilarating experience a bad habit on delicate new growth.
It's important to recognize which plants require a gentle touch. For example, many young maples and birches have thin bark that is easily marred. My first line of defense is to secure the trunks of these trees with tape, providing a protective layer when needed. I scrape off just the tape, then replace it with a fresh piece. This technique captures scales without requiring direct contact with the bark.
You should always follow your scraping with a full treatment. Any crawlers that you do not get will begin to rebuild colonies. I apply insecticidal soap two days after scraping and then monitor weekly. It is this integrated approach that cleared all of the scales from my Japanese maple without a single injury to the bark.
After scraping, prevent reinfestation. Release lady beetles, which feed on crawlers. If permitted, use systemic insecticides. I promote plant health with proper fertilization, which makes them less attractive to scales. These are effective ways to avoid reinfestation with the treatments remaining effective.
Read the full article: Mastering Scale Insect Identification: A Complete Guide
