Scale insects
Insects that sit still under a shell-like cover on stems and leaves, sucking the sap.
What you'll see
- Small brown, gray or white bumps that don't move, on stems, leaf veins and leaf undersides.
- Sticky honeydew and sooty mold with soft scales; armored scales leave no honeydew.
- Yellowing leaves, leaf drop and dying twigs when there are many.
Why it happens
Scale insects settle for life under a waxy or armored cover. Only the tiny newly hatched crawlers move around and spread.
How to fix it
- Scrape or wipe scales off with a soft brush or cloth, and prune out heavily covered twigs.
- Spray horticultural oil or insecticidal soap while crawlers are active, because adults are shielded by their covers.
- Squash a few before treating again: dry ones with no fluid are already dead.
- Use any spray exactly as the label says, and keep kids and pets away until it dries.
Keep it from coming back
- Inspect new plants, including leaf bases and the backs of fern fronds, before bringing them home.
- Keep plants well watered and healthy; they cope with a few scales.
- Protect ladybugs and tiny parasitic wasps by avoiding broad-spectrum sprays.
Read more
Sources
General guidance, not a diagnosis. For valuable, edible or outdoor crops, check with a local extension service or plant expert. Use any product exactly as its label says, and keep children and pets away while it dries.