Scale insects typically adhere to the stems, branches, and sometimes leaves of plants to feed on sap.
Below, learn how to identify, combat, and control scale insects on indoor and outdoor plants.
It is often confused for fungal or bacterial infections, like leaf spots or blight.
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Types of Scale Insects
Scale insects are closely related toaphidsandwhiteflies.
They vary significantly in color, shape, and size.They are often somewhat rounded, but not always.
Scale insects are usually divided into soft scale and hard or armored scale.
Armored scale secretes a hard shell over its body for protection from predators.
The shell also makes it difficult to use a pesticide because it has trouble reaching the insect inside.
Different species of scale insects favor different plants.Euonymus shrubsare frequently infested by scale.
Other common scale victims aremagnoliaandfruit trees.
However, you will never see just one of them, which makes them hard to miss.
Scale almost always appears in clusters.
The appearance of sooty mold on the plant is a sign of scale.
The blackish mold is one of the most visible indicators of scale.
Scale also causes cellular damage to the plant, making it structurally weaker.
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If left untreated, the scale will damage and weaken your plants and most likely cause them to die.
When to Combat Scale
Scale insects are adept at protecting themselves at most life cycle stages.
Now, the nymphs have legs and are actively crawling to find new spots to attach and feed.
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This is the time when they can be effectively killed with pesticides.
However, timing is everything, and there is a short window of opportunity.
Quick removal can prevent the scale from migrating to surrounding plants.
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However, if this is impractical, several control methods have proven effective against scale.
Inspect the plant thoroughly and any adjacent plants to ensure you have removed all infested stems.
Treat With Rubbing Alcohol
Rubbing alcoholcan kill scale insects if the infestations are light.
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The best approach is to put the rubbing alcohol directly on the scale bugs using a cotton swab.
Repeat every two to three days until the problem insects are eradicated.
Spray With Horticultural Oil
What Is Horticultural Oil?
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The oil is usually emulsified to make it easier to spray.
Spraying your plants withhorticultural oil is effective in late spring, just before the leaves unfurl.
Scale insects can overwinter as nymphs or eggs tucked away in tree bark.
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This software will smother the scale before the insects form their protective coating.
The oil coats the scale insects and clogs their breathing pores, suffocating them.
Apply with a spray bottle or garden sprayer until all the leaves are dripping.
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Warning
Only apply insecticidal soaps to well-hydrated plants, or you’ll risk damaging them.
Also, never use the product when the plants are in direct sun or above 90F.
Apply with a garden sprayer.
The Spruce / Phoebe Cheong
Other plant-based pesticides can also be successful.
you might encourage these natural predators by providing them with food and shelter.
it’s possible for you to also purchase beneficial insects by mail to release in your garden.
The Spruce / Phoebe Cheong
Synthetic chemical pesticides should be the last resort in the war against scale.
Don’t reach for a chemical pesticide unless all other methods have failed.
You must diligently control or remove scale when it infests indoor plants.
If you catch the problem early enough, pruning out the infested stems could alleviate the problems.
Keep a close eye on the plant for several weeks to ensure no new scale appears.
Dispose of thepruned stemsimmediately.
Remove existing scale on houseplants by rubbing gently with a facial-quality sponge or cotton swab dipped in rubbing alcohol.
Be sure to buy plain sponges without cleanser or lotion in them.
As always, test on a small area first since some plants are more sensitive than others.
Plants can survive scale and death from an infestation is rare.
However, a scale infestation can weaken plants or trees.
Use vinegar to remove scale insects up to a degree, but it may not be completely effective.
You shouldn’t need to dispose of your plant.
Quarantine it by keeping it at least 3 feet away from other plants while treating it.
If it’s badly infested, prune off infested branches.
If your plant looks dead or unrecoverable, discard it in the garbage.
Do not compost it.
Scale is very contagious and spreads quickly.
Isolate any plants with scale from your other plants, if possible.
Scale Insects on Shade Trees and Shrubs.Purdue University Extension.
University of California Integrated Pest Management.
Scale insects.Iowa State University.
