Treating and Preventing Scale

Treating and Preventing Scale

This entry was posted on March 18, 2015 by LemonCitrusTree .

Scale insects can be devastating to citrus trees. The pests are tiny insects which suck sap from the citrus tree and then excrete honeydew which accumulates on leaves, branches and fruit. Honeydew then turns to sooty mold and that interferes with photosynthesis in leaves, and can cause leaf drop and branch die back.

There are two types of scale, armored scales that are hard bodied consisting primarily of wax, the females of this family insert their long mouthparts as crawlers and never move again on their own, but can be moved by ants that are farming them. The soft bodied scale is not fastened permanently to the tree. The soft scale gives off large amounts of honeydew upon which sooty mold fungus forms, they can move on their own but often they are moved to other areas when ants relocate them.

It is important to have an ant barrier of a 3-4 inch band with tangle-foot around the trunk of the citrus to help protect ants from invading citrus. Since ants have a symbiotic relationship with scale insects (and other pests as well) a tape barrier is crucial. Ants domesticate many pests that damage plants and citrus trees, and ants will move those bugs from one food source to the next.

If you have an orchard, it is always a good idea to have a tape/tangle-foot barrier and to purchase Ladybugs and release those yearly. Ladybugs will attack all stages of scale.
If you notice beetles on your citrus trees, do not use pesticides. Beetles are keeping your trees healthy and will protect your investment.

Spraying soapy water onto the tree does little to remove scale insects. So it is always a good idea to completely wash citrus trees with Dawn dish-soap and warm water, with a wash-cloth. After washing treat tree with Horticultural Oil or Neem Oil.

Check tree again in a week and repeat process if required. It is always a good idea to wash the tree every time you fertilize.

If you need further assistance with a scale infestation, please message us here.

This entry was posted in Citrus Care and tagged citrus, scale, pests on March 18, 2015 by LemonCitrusTree . ← Previous Post Next Post →

Lemon Tree Pests: Tips Treating Pests Of Lemon Trees

You love your lemon tree, with its fragrant blossoms and juicy fruit, but insects also love this citrus. There are a number of lemon tree insect pests. These include relatively harmless bugs, like aphids, and more serious pests, like citrus rust mite, one of the insects that affect lemons rather than foliage. Read on for more information about how to get rid of insects on lemon trees.

Lemon Tree Insect Pests

Some lemon tree pests are insects that affect most of the plants in your garden. Aphids are a good example. Masses of these small insects appear with the new, green foliage in springtime. They can damage young trees if not controlled by natural predators such as the ladybug. Bringing in ladybugs to control aphids is a good, organic option for treatment.

If the leaves of your lemon tree curl and you see little passageways carved into the foliage, your lemon tree pests may include the citrus leaf miner. True to its name, a leaf miner mines passageways through the outer layer of leaves to feed on the soft tissue beneath.

These lemon tree insect pests can weaken a young tree, but make little difference to a mature, established tree. Natural predators are a big help in ridding the lemon tree of these insects. If you have a lot of lemon trees attacked, you can get these lemon tree pests by introducing another predator, the parasitoid wasp.

Treating Pests of Lemon Trees

You can sometimes get rid of insects on lemon trees by spraying the trees frequently with oil sprays. This treatment can be very effective for the Asian citrus psyllid. These small lemon tree insect pests cause damage to new growth as they feed, due to their toxic saliva. Oil sprays do not have the downsides of toxic pesticides, yet prove effective against these insects.

Horticultural oil sprays are also effective in treating pests of lemon trees known as citrus rust mites. These are insects that affect lemons, for the mites attack immature fruit. They can also attack foliage and leaves in some cultivars. Repeated oil sprays will get rid of insects on lemon trees.

Controlling Citrus Scale – How To Treat Types Of Scale On Citrus Plants

So your citrus tree is dropping leaves, twigs and branches are dying back, and/or the fruit is stunted or distorted. These symptoms may indicate an infestation of citrus scale pests. Let’s find out more about citrus scale control.

What are Citrus Scale Pests?

Citrus scale pests are tiny insects that suck sap from the citrus tree and then produce honeydew. The honeydew is then feasted upon by ant colonies, further adding insult to injury.

The female adult scale is wingless and often has no legs while the adult male has one pair of wings and notable leg development. Male scale bugs on citrus look similar to a gnat and are generally not visible and they do not have mouth parts to feed. Male citrus scale pests also have a very short lifespan; sometimes only a few hours.

What are the Types of Scale on Citrus Plants?

There are two major types of scale on citrus plants: armored scales and soft scales.

  • Armored scale – Female armored scales, from the family Diaspididae, insert their mouthparts and never move again – eating and reproducing in the same spot. Male armored scales are also immobile until maturity. This type of scale bugs on citrus exudes a protective coating made up of wax and cast skins of prior instars, which creates its armor. These citrus scale pests not only wreak the havoc mentioned above, but the armor will also remain on the plant or fruit long after the insect is dead, creating disfigured fruit. Types of scale on citrus plants in the armored scale family may include Black Parlatoria, Citrus Snow Scale, Florida Red Scale and Purple Scale.
  • Soft scale – Soft scale bugs on citrus also form a protective coating via wax secretion, but it is not the hardened shell that the armored scale produces. Soft scales cannot be lifted from their shell and females roam the tree bark freely until eggs begin to form. The honeydew secreted by the soft scale attracts the sooty mold fungus, which in turn covers the citrus leaves preventing photosynthesis. Once dead, the soft scale will fall from the tree instead of remaining stuck as the armored scale. Types of scale on citrus plants in the soft scale group are Caribbean Black Scale and Cottony Cushion Scale.
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Controlling Citrus Scale

Citrus scale control can be accomplished with the use of pesticides, biological control via the introduction of indigenous parasitic wasps (Metaphycus luteolus, M. stanleyi, M. nietneri, M. helvolus, and Coccophagus) and an organically approved petroleum spray, such as 440 oil Pure Spray Green. Neem oil is also effective. When utilizing any pesticide for controlling citrus scale, follow manufacturer’s instructions and spray the entire tree until it is dripping wet.

When controlling citrus scale, one may also need to eliminate the ant colonies, which thrive upon the honeydew extruded from the scale. Ant bait stations or a 3-4 inch band of “tanglefoot” around the trunk of the citrus will eliminate the ant marauders.

Citrus scale pests can spread rapidly as they are highly mobile and may also be transported on clothing or by birds. The best and first line of defense in controlling citrus scale is to buy certified nursery stock to prevent infestation from the get go.

Controlling Scale on Citrus Trees 2

Our lemon tree is bursting into bloom with the warmer weather

We’ve got a lemon tree growing in a large pot at the back doorstep. It’s just bursting in to bloom at the moment. Unfortunately we’re also starting to get a bit of scale appearing on the undersides of some of the leaves.

Scale are usually located on the underside of leaves and sometimes the stems of plants

If you’ve got scale on your citrus trees, you’ll probably also notice that there are ants crawling over your tree too. Scales shoot a sweet substance called honeydew. Ants like to ‘farm’ the scale to feed on the honeydew. They’ll even pick the scale up and move them all over the tree. Honeydew also leads to sooty mould, a black dusty fungus that grows over the leaves and stems. Controlling the scale will also get rid of the sooty mould.

Scale insects secret honeydew which in turn attracts ants

Scale in large numbers can cause leaf yellowing, leaf drop and die-back. Don’t worry though, it’s easily treated with a spray of white oil, which suffocates them. The great news is that it’s easy to make your own white oil to treat scale and aphids.

We’ve got a Meyer Lemon tree in a container at the back doorstep

How to Get Rid of the Insects on Your Lemon Tree

21 September, 2017

Lemon trees can easily become infested with insects, and getting rid of these insects can be easy or difficult, depending on the type of pest you’re dealing with. Your lemon tree is most susceptible to attacks by insects such as mites, brown soft scales, citrus thrips and whiteflies, and aphids. Orangedog caterpillars and snails can also create serious problems in your lemon tree. To control these lemon tree pests, you must use either a miticide, an insecticide, horticultural and dormant oils, Bacillus thuringiensis or an insecticidal soap.

Get rid of citrus bud mites and citrus red mites on your lemon tree by spraying the tree with a miticide during the summer months. Spray all the foliage on the tree according to the directions on the label.

Spray your lemon tree thoroughly with horticultural oil in early spring to control brown soft scale insects. In spring or mid-summer, when the scale insects are moving around and in the “crawler” stage, spray the lemon tree with an appropriate insecticide. Spray the lemon tree with a dormant horticultural oil in late winter to kill any over-wintering scale insects.

Control citrus thrips and Orangedog caterpillars by spraying your lemon tree’s foliage in early spring with a bacterial product, such as Bacillus thuringiensis (BTK). Spray your lemon tree again two or three times, every one or two weeks.

Get rid of citrus whiteflies on your lemon tree by spraying the tree with an appropriate insecticide. You may need to spray the lemon tree three or four times throughout the spring and summer to control the citrus whitefly infestation.

Spray the leaves of your lemon tree with an insecticidal soap in early summer to get rid of aphids. Apply the insecticidal soap to the leaves again in mid- to late summer if the aphids persist. If your lemon tree has a heavier aphid infestation, spray the undersides of the tree’s leaves and all other areas where the aphids are visible with an approved insecticidal spray.

If you have snails infesting your lemon tree, feeding on the leaves and lemons, place snail baits in rings on the ground around the tree trunk. Also, be sure to remove all fallen leaves and other debris, as well as prune away all low-hanging branches, to eliminate breeding and hiding places for the snails.

Always apply insecticidal products following the instructions on the label exactly. You should wear protective gloves and glasses when you’re handling and spraying these chemicals.

Treatment for Scale on a Citrus Tree

Citrus trees are susceptible to scales.

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Citrus trees are simple-to-grow flowering plants and provide a lovely fragrance for a home or garden. Small citrus plants grown indoors and outdoor citrus trees supply edible fruit for use in cooking and as gifts. Caring for citrus includes watching for infestations of damaging pests such as scales that cause unsightly vegetation and can destroy fruit and sometimes entire citrus crops.


Scales include two kinds of small insects that suck sap from plants. Armored scales have a hard, waxy shell covering a soft body. In addition to depleting plants of sap, some species of armored scales also inject toxins during feeding. Female hard scales never move after they pierce plants with their mouth parts and begin feeding. Soft scales, however, do not have a hard covering, and they look like raised spots. Scales vary in color. California red scale has a reddish-gray body while citricola scales have a spotted gray appearance.

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Severe infestations of scales result in falling twigs and branches until the affected tree dies. Soft scales produce a sticky substance called honeydew as they suck fluid, creating an environment ripe for the development of the fungal disease black sooty mold. Honeydew attracts ants that also can damage plants. It is simple to recognize citrus trees that have black sooty mold because their leaves, twigs and branches turn black. The mold also reduces the trees’ ability to conduct photosynthesis.

Biological Controls

Biological controls can be an effective treatment for scales on outdoor citrus trees. Natural enemies of the pests include vedalia beetles (Rodolia cardinalis), adult Australian lady beetles (Rhyzobius lophanthae), twicestabbed lady beetles (Chilocorus orbus) and parasitic flies (Cryptochaetum iceryae). Beetles attack all stages of scale. The larvae feed on scale eggs, and the adults attach themselves to egg sacs and hatch underneath scales. Parasitic flies also feed on the body of scales and hatch eggs inside the scale bodies. They also use the remains of scales during pupation. Vedalia beetles and parasitic flies live in coastal areas and prey on cottony cushion scale. Twicestabbed lady beetles and Australian lady beetles attack brown soft scale.

In order to ensure that your lawn keeps a healthy population of beetles to attack scales, control ant infestations with bait and other measures. Also keep citrus areas free of dust. If you see beetles on scales, then you do not need to resort to using pesticides. They are an effective biological treatment. You can move them manually to infested citrus trees.

Horticultural Oil Sprays

Gardeners use spray oil as a selective pesticide treatment for scale on citrus trees. Petroleum-based oils reduce the amount of scales. The oil asphyxiates pests by blocking air holes, inducing suffocation. Completely moisturize soil before using an oil. Pay attention to temperature and humidity requirements on the product’s labels. In a coastal location such as San Francisco, oil should not be used when the temperature will be higher than 85 to 90 degrees Fahrenheit or the relative humidity is less than 30 percent. Also avoid using oil if the temperature is below freezing or during, prior to or after abnormally cold temperatures. Cold temperatures lead to uneven coverage because the oil emulsion breaks down. Spray oil application occurs once or twice per year. Several brands of oil are on the market for home use and available at plant nurseries.

Lemon Tree Bug Remedies

About the Author:

Jean Godawa

Jean Godawa is a science educator and writer. She has been writing science-related articles for print and online publications for more than 15 years. Godawa holds a degree in biology and environmental science with a focus on entomology from the University of Toronto. She has conducted field research in the tropical rainforests of southeastern Asia and South America.

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Whether you grow it for its fresh fragrance, showy flowers or versatile fruit, the lemon tree (Citrus limon) does well as an outdoor tree or an indoor potted plant. It grows outdoors in the warm climates of U.S. Department of Agriculture plant hardiness zones 9 through 11, and is vulnerable to frost, bacterial infection and a variety of pests. The appropriate pest treatment depends on the kind of damage and the type of bug.

Lemon Pests

Leaf-dwelling lemon pests include mites, snails, aphids, psyllids and mealybugs. Adult Diaprepes root weevil, an introduced pest, feeds on lemon foliage while its larvae feed on the roots, causing extensive damage. Red imported fire ants damage twigs and bark of young lemon trees. Scale insects target the leaves and twigs of the lemon tree and can cause significant damage.

Cultural Controls

Wrap the lemon tree trunk with a band of copper foil to deter snails. Use sticky horticultural tape around the trunk and prune branches up to 30 inches from the ground to block ants and other non-flying leaf pests. Keep the tree healthy to prevent damage from root weevils with proper watering.

Natural Predators

Natural predators generally control lemon tree pests. Ladybugs, lacewings, syrphid flies and parasitic wasps target aphids, scale, mealybugs, root weevils, mites and psyllids. Avoid using broad-spectrum insecticides in your garden because they kill both beneficial and pest insects. Plant a variety of plants with nectar and pollen sources around the edge of your yard to invite and maintain beneficial insect populations.

Horticultural Oil

When natural predators aren’t keeping bugs in check, horticultural oil helps eliminate most leaf-dwelling lemon tree pests without adverse effects on people, wildlife or the lemons. The oil, available at garden centers, works on contact by blocking the pests’ breathing tubes. Mix 2 1/2 ounces of horticultural oil and 1 gallon of water in a garden sprayer. Spray all surfaces of the lemon tree’s leaves, along with the stems and twigs where bugs may be hiding. Apply on a calm, mild day. Avoid breathing the mist and protect your eyes while spraying. For indoor lemon trees infested with aphids, mealybugs or mites, wipe the pests off with a cotton swab soaked in isopropyl alcohol. Repeat the process a week later to get rid of any subsequent generations.

Scale Insects

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What are Scale Insects?

There are two main groups of scale insects, both of which spend most of their lives as immobile adults under a coating, sucking the sap from stalks, leaves and stems.

Hard scale (for example red citrus scale) has an oyster like coating and is difficult to control. Also known as armoured scale.

Soft scale (for example pink wax scale and soft brown scale) are usually found on the mid-rib of leaves and stalks of host plants.

Most common is white wax scale, seen as large patches of white waxy material along the stems and shoots. The wax covers the insects which feed on the sap. The adult scale lays up to 1000 eggs that hatch into crawlers. These crawlers move to a nearby feeding site where they set up home feeding on the sap of the plant. It is at this crawler stage the scale is most vulnerable as there is no waxy coating to protect them.

Turn the leaves over and look for small raised bumps. Scale insects are tiny creatures that hide underneath a protective covering and suck the sap out of leaves.

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Yates Nature’s Way Citrus & Ornamental Spray is a ready to use, organically certified blend of pyrethrin (an extract from the pyrethrum daisy) and vegetable oil. Regular spraying on the undersides of the leaves (so it comes into direct contact with the scale) will help bring scale insects under control.

NOTE: There are other different types of scale and some scale insects are host specific, such as rose scale, white palm scale, gum tree scale and tea scale (camellias). Others attack a variety of hosts such as white wax scale occurring on gardenias and citrus; and cottony cushion scale occurring on figs, rose, magnolias, grevilleas and citrus.

How to Protect your plants from Scale Insects

Scrub off plants or spray with Yates White Oil, preferably in summer when scale insects are breeding.


If your citrus tree is dropping leaves, twigs and branches are dying back, and/or the fruit is stunted or distorted. If you’ve noticed small yellow spots appearing on your citrus leaves any of these symptoms may indicate an infestation of citrus scale pests.

Other signs are white patches on stems or pink or brown raised dome like structures on leaves and stalks about 3-5mm.

Sooty mould grows on the honeydew the scale insects secrete. Scale can cause death of stems if infestation is heavy.


Term applies to small insect of the order Hemiptera, suborder Sternorrhyncha. There are currently around 8000 known species of scale insects.

Scale are small sap-sucking insects. Many look like the scale of a fish or lizard, while others can even appear fluffy. The scale insects that most gardeners are familiar with are the adult females. The adults are generally immobile and are permanently attached to the plant that they are sucking the sap from. Scale feeding on a plant can affect the vigour and also produce honeydew.

Honeydew is a sweet waste product that can attract wasps and cause your plants to become covered in sooty mould.


Healthy plants are less likely to suffer from insects like scale. Feed plants regularly, do what you can to improve the soil and make sure that plants are well watered.


Spray plants thoroughly (until they start dripping) with Bugtrol.

It’s an organic spray but, if possible, spray in the evening to avoid harming any beneficial insects in your garden.

Don’t use oil-based sprays on ferns or fine-leafed palms. For these plants either use pyrethrum or see the other treatment option.

Other Options

Use Conqueror oil over your infected plants. Make sure to spray on non-flowering plants, or take the flowers off any bee-friendly plants before spraying.

If possible spray in the evening to reduce harm to the beneficial insects in your garden.

A Home Remedy for Aphids on an Inside Lemon Tree

A Home Remedy for Aphids on an Inside Lemon Tree

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Lemons and other citrus trees kept indoors year-round or moved inside only during cold weather are prone to most of the same pests as citrus cultivated outdoors. Pests like aphids and spider mites are often especially damaging on plants moved or kept indoors because few natural predators are present and conditions sometimes favor the rapid growth of pest populations. The indoor location and often small size of a lemon grown indoors makes the use of potentially harmful and costly pesticides less desirable than relatively safe and affordable home remedies.

Water Spray or Wiping

If the lemon tree and container are small enough to fit in a large sink or tub inside or are easily moved outside and weather is mild, a strong spray of water knocks the aphids off of the plant. Water also rinses off honeydew and any sooty mold that has formed on the honeydew. Aphids tend to congregate on the undersides of leaves, so pay special attention to that area when spraying with water. An additional aphid control that is most effective when the pest population is small and concentrated primarily on a few leaves is manual removal of those heavily infested portions or physically squashing the aphids.

Soap Spray

A soap spray to control aphids and other pests like mealybugs, thrips and whiteflies is made by combining about two teaspoons of mild, pure soap with no additives and a quart of water. The spray must thoroughly cover both sides of all leaves and the entire stem. Adding a small amount of vegetable oil increases the effectiveness of the spray. If there is concern that the solution will burn the lemon tree leaves, rinse it off after a few hours. Two to three repeat applications of this spray spaced three days apart are likely necessary. If aphids persist, increasing the concentration of soap slightly, but not so much that it burns leaves, will help to curb the pest population.


Dipping a cotton ball or swab in a solution of half water and half rubbing alcohol then wetting the aphids is a potential control option when the pest population is fairly small and clustered. Testing the solution in a small, inconspicuous portion of the plant before implementing it widely is important to ensure that it will not burn the lemon tree’s leaves.

Additional Homemade Sprays or Repellents

Numerous additional home remedies may offer control for or prevent the presence of aphids. A dusting of potato flour or a spray of potato starch dextrin and water forms a sticky trap on leaves that holds pests in place until they die. Various pureed mixtures that contain a blend of ingredients that aphids find unpleasant like jalapeno or cayenne peppers, garlic, spearmint or onion tops combined with water and perhaps a small amount of rubbing alcohol or oil may offer some degree of aphid control if thoroughly and repeatedly sprayed onto the lemon tree leaves.

Cultural Care

Certain care techniques or considerations allow a lemon tree kept indoors to recover from aphid feeding and any pest treatments that damaged the plant without leaving the plant newly vulnerable to additional feeding. Removing potential sources of aphids like nearby weeds or other houseplants, screening nearby windows, vents or doors and rinsing off the plant regularly or when it is moved indoors seasonally reduces the presence of aphids. Avoid the use of excessive fertilizer, as nitrogen encourages vulnerable new growth that is attractive to aphids. Provide the lemon tree with adequate water and ample sunlight.

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