Scale Insects Treatment for a Healthy Lawn and Garden

Scale insects can be a real nuisance for gardeners and homeowners. They're tiny, armored insects that feed on plant sap, causing curled or distorted leaves, and stunted growth.

Scale insects can be found on a wide range of plants, including trees, shrubs, and houseplants. They're particularly fond of plants with soft, tender stems.

To treat scale insects, it's essential to identify the type of scale you're dealing with, as some species are more resistant to treatment than others. Some common types of scale insects include cottony cushion scale, soft scale, and armored scale.

Regularly inspecting your plants for signs of scale insects is key to catching the problem early on. Look for small, white eggs, or tiny, brown insects on the stems and leaves of your plants.

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Before treating scale insects, it's essential to check their viability on a plant. You'd be surprised how many dead scales are stuck to the tree or shrub, up to 75 percent or more.

Applying an insecticide to a dying population of scale insects may kill mostly the natural enemies that help keep the population under control. This can lead to a rebound in scale and mealybug levels, making the problem worse.

To determine if a scale insect is alive, use a small sewing needle and a hand lens to flip over the waxy coating. If it's alive, it will look full and rounded under the waxy coating, and may even bleed when uncovered.

If you've determined that most scales are dead, you can rely on a dormant oil or insect growth regulator spray to reduce populations further over time and protect natural enemies.

Physical removal is the most environmentally-friendly approach to treating scale infestations, but it's not always practical because scale often populates inaccessible plant parts.

In some cases, it's simply not feasible to remove scale from hard-to-reach areas of a plant. Refer to the mechanical section for details on alternative methods.

Potted plants with moderate scale populations can be isolated to prevent the infestation from spreading to other plants.

Replacing plants that are susceptible to scale insects is a viable option, but you'll need professional identification of the scale to choose the right replacement.

Some scales can attack multiple plant types, so getting the right ID is crucial. This technique can be effective, but it requires careful consideration.

You can also use a consumer-grade pressure washer to dislodge scale insects from plants, but be cautious with the tip you use. A broad tip is safer than a pinpoint tip, which can severely injure plants.

Properly timed, using a pressure washer can be done once or twice a year and help reduce sooty mold.

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Natural control is a great way to manage scale insects, and it's actually easier than you think. Populations of scale insects are often kept in check by natural enemies, which are insects that prey on them.

Parasitoids, like wasps or flies, use scale insects as food and a place to develop. They emerge from the host insect, leaving small holes in the waxy scale cover.

Predatory insects, mites, spiders, and pathogenic fungi also commonly attack scale insects. This means that in a natural setting, like a woodland, beneficial insects like lady beetles and microscopic wasps can keep scale insect numbers quite low.

In fact, these natural enemies can be so effective that it may not be necessary or feasible to use chemical controls.

Chemical control is a common method for treating scale insects, but it's essential to use it wisely. Chemical insecticides can be necessary to prevent plant loss or unsightly infestations.

Different insecticides may be required at different stages of the scale insects' life cycle. For example, crawlers are the easiest stage to control, and contact active insecticides, insecticidal soaps, azadirachtin products, oils, and insect growth regulators (like Distance) are effective against them.

Systemic insecticides are best used against nymphs or adults in the spring to summer, while horticultural oils and systemic insecticides are effective against armored scales during this time. In the late fall to winter, horticultural oils are the best option for controlling adult armored scales.

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If you're not getting good results with manual removal efforts alone, consider removing and replacing infested plants. This is especially recommended for invasive species. Before using pesticides, identify the species of scale insect, as this will help you know when to apply control measures.

To minimize harm to natural enemies, apply the fewest treatments at key times. Crawlers, being vulnerable and without a protective shell, are more susceptible to minimal-toxicity pesticides than settled scale. For species with overlapping generations, monitoring and treatment may need to occur several times a year for effective control.

There are two main windows of opportunity for applying pesticides: during crawler activity and during the dormant season when juveniles overwinter. Always follow product label instructions and remember that dead scales don't fall off immediately.

To use horticultural oil effectively, use a 1% dilution rate and ensure thorough coverage, coating all bark or leaf surfaces. Repeat applications may be necessary if the crawler activity window is long. For dormant oil applications, use a 1% dilution rate and ensure thorough coverage of all bark surfaces (and foliage for evergreens).

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Scale insects are a type of pest that can be difficult to control due to their protective waxy armor.

They spend most of their lives feeding on the same spot of a plant, and are unable to walk until they hatch from eggs.

Scale infestations spread when crawlers, the young scales, walk or are blown by the wind to nearby plants or plant parts.

Crawlers are small, flattened, and look like dust on the plant surface.

Females can produce about 100 eggs each.

Winged males crawl out from beneath their cover to mate with covered females.

Soft scales, on the other hand, are not covered by a waxy shell.

Crawlers that hatch from eggs in mid-summer will usually crawl directly to leaves.

They spend most of the summer feeding on leaves and excreting honeydew.

Winged males mate with wingless females, who swell with up to 1,000 eggs.

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Inspect your plants regularly for live scale infestations, which can be identified by suspicious-looking bumps on twigs and branches.

These bumps can be flipped over with a thumbnail to check if the bark is intact beneath, a sign that the plant may have live armored scales.

If the soft body beneath a cover is visible, it's likely that the plant has live soft scales or mealybugs, which can be indicated by honeydew falling from the tree.

Leaves should be inspected for live soft scales or mealybugs if honeydew is present.

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Inspect your plants regularly for live scale infestations, as they can cause significant damage if left unchecked. Check for suspicious looking bumps on twigs and branches with a thumbnail, as the bark is usually intact beneath a scale.

A live armored scale will have a soft body beneath a cover, whereas other types of scales can be squashed and are not as concerning. Honeydew falling from a tree is a sign that you should inspect your leaves for live soft scales or mealybugs.

More than 60 different kinds of scale insects occur in Indiana, and they're often overlooked until tree or shrub branches start to die.

These pests damage plants by sucking out plant juices, causing them to become unsightly and potentially stunted.

Honeydew, a sugary liquid produced by some scales, can create a sticky mess on parked cars, walks, and benches beneath infested trees.

Sooty mold, a black fungus that feeds on honeydew, can further harm plants by shading leaves and reducing growth.

Soft, kermes, and bark scales produce honeydew, while armored and pit scales do not.

Armored scales feed on plant contents by bursting plant cells with their straw-like mouth, while pit scales likely do the same to the raised plant tissue surrounding them.

Scale insects are considered pests because they consume sap or plant cell contents, and their populations can quickly get out of hand.

Scale insects are categorized as either armored (hard) scale or soft scale, and this distinction determines the damage they can cause and how they are best controlled.

Low populations of scale insects tend to go undetected, but high populations can cause plant damage such as leaf yellowing, plant stunting, or branch dieback.

Large numbers of soft scale insects also contribute to sooty mold growth, which can further damage your plants.

Understanding the life cycle of scale insects is key to managing them effectively, with the crawler stage being the most vulnerable to insecticides.

Here are some key differences between armored and soft scale insects: