How To Treat Scale On Outdoor Plants

One of the more frequent insect species that assault plants is the scale bug. They may be found grazing on bushes, trees, and even houseplants.

Scale insects move when they first emerge from their eggs. They are known as crawlers at this stage and are really little. These crawlers go mostly unnoticed by gardeners.

They never move again and securely cling to a leaf or stem after they settle down to eat and pierce the plant’s tissue with their needle-like mouthparts. Scales also wrap their bodies in a waxy substance that both conceals and protects them. Many gardeners wait until the plant is severely infested and damaged before realizing there is an issue.

There are many different types of scale insects, but these are some of the most typical. Tea scale insects are around the size of a hyphen, white or brown in color, and slightly fuzzy. They are a serious holly and camellia pest. Florida wax scales, which can be found on a wide range of plants, resemble waxy, white domes that are roughly the size of a nail head. On the other hand, tea scale-looking euonymus scale assaults euonymus. False oleander scale on magnolia trees appears as tiny white bumps on the leaves, whereas magnolia scale on the branches looks like yellow waxy blobs that are between a quarter and a half an inch around. On ficus, schefflera, and other indoor plants, there is soft brown scale. On the fronds, fern scale appears as white dashes. There are a lot more.

When scale insects consume a plant’s sugary sap, some of the sugar is excreted in a liquid known as honeydew. The leaf can become sticky and shiny as a result of the honeydew accumulation.

This abundant food source is well known. The tasty honeydew may draw ants, wasps, and other insects. Even more frequent is the development of sooty mold, a fungus that gives leaves an unsightly black coating. Although these fungi eat the honeydew rather than immediately attacking or harming the plant, the development of sooty mold is frequently the gardener’s first warning sign of trouble.

Be mindful that aphids and whiteflies are two more sucking insects whose honeydew can cause sooty mold to grow. Additionally, some scales, such as tea scale, do not produce sooty mold.

Scales are little, leg-equipped crawlers that move around from plant to plant. Contact pesticides like insecticidal soap or malathion can be used to control crawlers, but most gardeners are unaware of them and lose the chance. In the spring, many scales generate crawlers. Insecticides applied directly to the crawlers lose most of their effectiveness once they have settled down to feed and have formed their protective covering.

A horticultural oil spray is the most secure and efficient method of controlling scale. Oil is present in these insecticides in a form that will mix with water. The oil coats the scale insects and blocks their breathing pores when combined and sprayed onto an affected plant. Instead of being destroyed by a toxin, the insects suffocate. Spray oils come in the Volck (for use in cool weather), All Seasons, and Year-Round brands.

It is essential to spray the oil on all surfaces of the plant for effective control. The oil won’t affect the insects if they are on the underside of the leaves and the oil is just sprayed to that surface. Scale insects are challenging to eradicate, so one or two further applications should be performed after the initial one. the instructions on the label attentively.

Oils are less hazardous to helpful predatory insects than other insecticides, but they are still effective against aphids, whiteflies, spider mites, and the crawling stage of scales.

Oil sprays should only be used on plants that are not under stress, and they work best when the temperature is between 45 and 85 degrees. The mild spring weather is ideal for using them in part because of this. However, during the summer you can use a light paraffinic oil like Year-Round spray oil or All Seasons spray oil.

Oil sprays also assist in cleaning the plant of the ugly sooty mold, which is an added bonus. When the scale is under control, the sooty mold won’t go away right away, but when the food source runs out, it will slowly weather off. Oil mists hasten the process.

Scale management can also be accomplished with systemic pesticides. These insecticides are applied to the plant’s roots or sprayed on the plant itself. The insecticide is absorbed by the plant into its tissue, where it enters the circulatory system and sap. Scale consume the poisonous insecticide while consuming the sap, which kills them.

Scale can be controlled with three regularly used systemic insecticides: acephate, imidacloprid, and dinotefuran. Pouring the combined pesticide at the plant’s base is the recommended treatment. When temperatures prevent the use of an oil spray or when flooding the area surrounding the plant’s base is more practicable, systemic insecticides offer a control option. When using any pesticide, always read and carefully follow the label guidelines.

How can scales on outdoor plants be removed?

Since most insecticides are rendered ineffective by scale’s protective layer, treating it can be challenging. The best way to control infestations is through natural or mechanical controls. Try the following techniques if scale insects are present:


Keep an eye out for scale on your plants since once the soft or hard shell has formed, no insecticide will work. When the insects are most vulnerable, in the spring, watch for the initial crawler stage; cleanse the area before applying a spray.

Use water:

Use a mild hose blast to loosen eggs, nymphs, or adults from small infestations. To kill them, dispose of in a bucket of soapy water. Those stems or leaves that have sooty mold should be cleaned.

Use natural predators:

Scale-eating insects provide organic pest control. These include ladybugs, soldier beetles, parasitic wasps, and lacewings. Create habitat to draw and maintain these insects. You can order beneficial insects online or at your local garden center.

Apply horticultural oil:

Neem oil, an organic horticultural oil, works on eggs, nymphs, and adults because it coats and suffocates the insects. Don’t forget to adequately cover the entire plant. Applying oil in the spring before leaves appear will help control insects and overwintering eggs. Multiple applications can be required. Carefully follow the directions since some plants could be sensitive and because applying oils requires a specific range of temperature.

Use insecticidal soap:

Use a store-bought insecticidal soap or make your own. The crawler stage, before the scale develops its protective layer, is when this therapy is most effective. Multiple applications can be required.

What produces scale on plants in the outdoors?

According to an Army Corps of Engineers report, over half of the expansive marshland in the lower Mississippi River Delta has withered or died recently.

As newly hatched crawlers, which are quite tiny, have legs, and can move around, scales spread from plant to plant. With the use of readily accessible contact insecticides, crawlers can be controlled pretty easily. Scale crawlers can be challenging to find, unfortunately. The majority of gardeners overlook them and lose the chance to exert control.

In the spring, many scales generate crawlers. Insecticides applied directly to the crawlers lose most of their effectiveness once they have settled down to feed and have formed their protective covering.


In general, scales are not one of those insect pests that will simply disappear over time if you ignore them. Most of the time, control is required.

Oil sprays are the most eco-friendly and efficient pesticides for controlling scale. Oil is present in these insecticides in a form that will mix with water. The oil coats the scale insects and blocks their breathing pores when combined and sprayed onto an affected plant. Instead of being destroyed by a toxin, the insects suffocate.

Heavy oils like Volck Oil Spray and light oils like Year Round Spray Oil, All Seasons Oil Spray, and others are marketed under specific brand names. The fact that mild horticultural oils can be used all summer long is why I enjoy them.

It is essential to spray the oil on all surfaces of the plant for effective control. The oil won’t affect the insects if they are on the underside of the leaves and the oil is just sprayed to that surface. Due to the difficulty in getting rid of scales, the label’s instructions should be followed for a second and even third application.

Aphids, whiteflies, spider mites, and the crawling stage of scales can all be successfully controlled with oils. Oil sprays do not leave behind a residue that can harm beneficial insects, in addition to having a low toxicity.

Oil sprays also assist in cleaning the plant of the ugly sooty mold, which is an added bonus.

What is the ideal method of treating scale on plants?

Despite your best efforts, nature will occasionally take its course and you will need to regard your plant as a scale. The backside of these small insects’ shells reveals that they have securely attached themselves to your plant and are actively draining its sap away, despite the fact that they can resemble benign brown growths on your plants.

Scale can be any color, shape, or size, but it most frequently takes the form of small, brown, spherical lumps on the leaves and stems of your plant. There are two basic categories of scales: unarmored or soft scales and armored or hard scales. The names allude to the insect bodies’ protective shell-like covers. The protective scale that the insect is covered with makes control difficult, as it is with mealybugs. Scales can be round, oval, or oyster shell shaped, and they can be up to 1/8 inch long. They are primarily brown in color, but they can also be white or black.

Under their shells, females can lay hundreds of eggs, which hatch into 1/100-inch-long, translucent worms. The initial few seconds of a scale’s life are spent moving around until they cling onto a plant’s leaf permanently. These defenseless crawlers, however, go on to fresh feeding grounds where they affix to the plant and create their own protective shells. Since it’s uncommon for a plant to have only one scale, there probably are more lurking beneath the surface. Treat your plant as soon as you see any symptoms to save it from becoming overwhelmed.

The safest way to start treating scale, whether it has a soft or hard shell, is to start by removing the pests with your fingernail, a soft toothbrush, or even a Q-tip dipped in rubbing alcohol. Soft shell scale bugs can be susceptible to insecticide. Most can be easily taken off the plant with a little bit of push, while tougher adults can sometimes be more resistant. To get rid of any stray bugs you may have plucked off but dropped into another area of the plant, rinse the plant under the sink or shower faucet. While doing so, take care not to moisten the soil excessively.

In order to treat any remaining larvae, the next step is to apply an insecticide. It’s crucial to treat the entire plant with your selected insecticide even if you manually removed every bug because the larvae are so minute they may still be present. Neem oil is recommended as an all-natural, organic therapy and preventative measure, but insecticidal soap may be more effective for severe infestations. Simply use either mixture to evenly mist the entire plant from top to bottom, then use paper towels to clean the foliage. Please take note that sunlight mixed with the insecticide might burn a plant, thus insecticide should only be used at night or when the plant is out of direct sunlight.

a severe infestation of scales. Notice the buildup of scale close to the stem, which is the leaf’s juicier and more nutrient-rich area.

While it heals, keep the afflicted plant separate from the rest of your collection, taking extra care to make sure that none of its leaves touch those of any other plants. Continue using this method every 7 to 10 days until the scale bugs stop appearing. Make sure to periodically and completely inspect all plants for future prevention. A nice addition to regular plant maintenance is dusting leaves and checking for pests.

How can you naturally treat plant scales?

These sap-sucking bugs cling to host plants’ twigs, leaves, branches, and fruits. Learn about the least-toxic ways to control the scale here.

Over 1,000 species of scale insects are found in North America, and they are frequently seen on houseplants, ornamental shrubs, backyard trees, and greenhouse plants. They are so strangely formed, stationary pests that they frequently resemble bumps, not insects. In many instances, severe infestations develop undetected before plants start to experience damage. It’s possible for large populations to cause poor growth, diminished vigor, and chlorotic (yellowed) leaves. A host that has been infected could die if the infestation is not stopped.


There are two categories of scale insects:

Armored (Hard)

secrete a tough, non-body-attached coating (1/8 inch long) to protect themselves. Under this spherical armor, the hard scale feeds and lives, but it does not move around the plant. No honeydew is secreted by them.

A waxy film, up to 1/2 inch long, that is a component of the body is called SoftSecrete. They frequently have the ability to travel small distances (though they do so infrequently) and make a ton of honeydew. Soft scales can be flat or nearly spherical in form.

Life Cycle

Under their protective covering, adult females lay eggs that take one to three weeks to hatch. The newly hatched nymphs (known as crawlers) emerge from this covering and travel around the plant until they find an appropriate eating place. Young nymphs pierce the plant with their mouthparts and start to feed. As they get older and become immovable adults, they eventually construct their own armor. They do not pupate and, especially in greenhouses, may have numerous overlapping generations per year.

It should be noted that many species’ males grow wings as adults and resemble tiny gnat-like insects. They don’t eat vegetation and are rarely spotted. Females frequently procreate without sex.


  • Pruning and discarding infected branches, twigs, and leaves will help get rid of scale insects.
  • When scale counts are low, they can be manually rubbed or plucked from plants.
  • When infestations are mild, dabbing individual pests with a cotton swab dipped in alcohol or a leaf shine containing neem will also work.
  • Ladybugs and lacewings, two helpful insects that are sold commercially, are predators of the immature larval or “crawler stage.”
  • The larvae can also be eliminated with natural insecticides such as d-Limonene and insecticidal soap. The environment does not retain these compounds very well, thus many treatments throughout egg hatching will be necessary for efficient control.
  • The main insecticidal component of neem oil, azadirachtin, may be found in Azamax. With its numerous modes of action and organic approval, this concentrated spray essentially eliminates the possibility of pest resistance growing. The best part is that it doesn’t harm honey bees or many other useful insects.
  • All pest life phases, including adults that are shielded from most other pesticides by their armor coats, are controlled with horticultural oils and other safe, oil-based insecticides.
  • As a last option, quick-acting natural pesticides should be utilized. These natural insecticides, which are derived from plants with insecticidal qualities, have less negative side effects than synthetic chemicals and degrade more quickly in the environment.

Advice: Ants will defend these pests from their natural predators and eat on the honeydew that sucking insects produce. To naturally get rid of ants, apply Tanglefoot Pest Barrier to the trunks of trees or the stalks of woody plants.