Scale

Immobile bumps glued to stems and leaf undersides — waxy brown domes, white cottony cushions, or gray crusts depending on the species. They do not look alive until you flick one off; sticky honeydew and sooty mold usually give them away.

Pest46 plants we cover get scalemostly trees

Pest checklist

Four things to look for. If most of them match what you are holding, you are in the right place.

Immobile bumps glued to stems and leaf undersides
Waxy brown domes, white cushions, or gray crusts
They flick off with a fingernail
Sticky honeydew and black sooty mold below

What gets rid of them

Gentlest option first. For most backyard cases the first one is enough, so try these in order and stop as soon as it works. If you do spray something, the product label tells you how — please read the notice further down.

1Scrape and swab
On houseplants, a fingernail or alcohol-dipped swab removes adults faster than any spray reaches them under their armor.
isopropyl alcohol 70 percentTry this first
2Horticultural oil at the crawler stage
The one window scale is vulnerable: the mobile hatchlings. Dormant-season oil on woody plants smothers overwintering stages too.
horticultural oil spray
3Prune out encrusted wood
A branch shingled in scale is a source, not a patient.

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Which plants get scale

Every plant we cover that gets scale, grouped by type — tap any one to open its page. A note beside a plant came from that plant’s own entry, because the same pest can be a minor nuisance on one plant and a serious problem on another. Plenty of plants we do not cover get it too.

trees16

shrubs8

vines2

perennials2

succulents3

cacti2

houseplants13

Plant families hit hardest

Related plants often share the same problems, so if one plant in a family has it, check the others. The largest group here is Rutaceae, with 7 of the 46 affected plants.

Rutaceae7 plants
Asparagaceae3 plants
Magnoliaceae3 plants
Moraceae3 plants
Oleaceae3 plants
Aquifoliaceae2 plants
Araceae2 plants
Cactaceae2 plants

When to treat

Easiest to kill as crawlers in early summer. Dormant oil in late winter handles the rest.

On specific plants

Bay Laurel
Growing
Dab scale with alcohol swabs; check leaf undersides monthly indoors.
Calamondin Orange
Growing
Oil for scale; check monthly indoors.
Common Lilac
Dormant
Dormant oil if scale builds.
Crape Myrtle
Dormant
Dormant oil if bark scale arrives.
Grapefruit
Growing
Oil for scale; certified stock in FL/CA/TX.
Kumquat
Growing
Horticultural oil for scale.
Lime
Growing
Oil for scale.
Mandarin / Tangerine
Growing
Oil for scale.
Orange
Dormant
Horticultural oil in late winter for scale.
Growing
Oil for scale; buy certified disease-free stock in citrus states.
Osmanthus
Growing
Horticultural oil for scale if needed; improve drainage.
Saucer Magnolia
Dormant
Horticultural oil for magnolia scale.
Growing
Oil for scale.
Yaupon Holly
Growing
Horticultural oil only if scale is heavy.
Yuzu
Growing
Oil for scale.

Timing only — the label is the law

This page tells you when to watch for scale and when treating is worth considering. It is not a recommendation to apply any particular product. Read and follow the product label before you spray — under federal law the label is the legal instruction, and using a pesticide against it is illegal.

Check the pre-harvest interval. Every product that’s cleared for an edible crop sets a minimum number of days between spraying and picking. Find it on the label before you spray anything you intend to eat.
Check the re-entry interval before you or anyone else works in the treated area again, and use the protective equipment the label names.
Confirm the product is registered for your crop in your state. This page groups many different crops together, and a product legal on one of them is not legal on all of them — state registrations differ too. Your state pesticide agency or local extension office can confirm both.
Rates and mixing instructions come from the label, never from us. We don’t publish them because they differ by product and formulation.