Soft scale bugs are so common on indoor and outdoor plants that you expect an infestation at least once.
The brown scale (the Coccus hesperidum) is the most common type of soft scale you’ll find on an indoor plant.
They’re also one of the ugliest pests. They resemble flat brown slugs embedding themselves into the leaves of a plant. It’s not a pretty sight at all.
They’re a pest you should always be on the lookout for. Soft brown scale bugs aren’t easy to miss if they’ve taken over your plants.
They’re also not easy to get rid of once you have an infestation.
Like most of the pests that infest indoor plants, the brown scale feeds off of the sap. When enough of these bugs are feeding off of your plant, they’re sucking the life out of it.
So, how do you avoid brown scales? What should you do if brown scales infest and attack your plant?
We have the answers to all your questions about soft scales. We’re going to learn everything there is to know about these pesky pests.
Other plant pests are mealybugs and aphids. We also wrote extensive articles about these pests and the best ways to get rid of them that you can consult here:
Full guide about how to detect mealybugs and get rid of them
What are aphids? How to spot and remove them
What are Brown Scales?
The brown scale bug comes from the Coccidae family.
Like the Pseudococcidae, these scale bugs don’t have armor to protect themselves.
They grow to be between two and a half millimeters to five millimeters in length.
The females are in the shape of an oval and they’re wingless.
There are no identifiable body parts on these bugs. They also have long antennas that are almost impossible to see.
They can be a yellow-brown or a green-brown. But they’re usually a red-brown color.
As they get older, they start to get darker and darker in color.
The brown scales have mouths that can pierce through the plant to get to the sap.
Their mouths also can suck the sap so they can ingest it. These mouths look small straws if you are looking under a microscope.
Nymphs (or crawlers) produced by the females are oval too. They’re flat and you can almost see through them.
They’re so small, they look like a speck to the naked eye.
Male brown scales are very, very rare. They’re usually smaller than their female counterparts. They have wings and a long antenna.
The scales aren’t too picky on what plants they take over and feed from. But their favorite plants are citrus plants.
There are a few other soft scale bugs that can take over indoor plants. Some of the most common include:
- Calico scale
- Cottony camellia scale
- Fern scale
- Lecanium scale/Fruit lecanium scale
- Magnolia scale
- Wax scale/Indian wax scale
Other types of soft scale bugs differ in appearance, in how they reproduce, and how you rid your plant of them.
How Brown Scales Reproduce
A female brown scale creates about 250 eggs (or ovisacs) in their lifetime.
In one year, they can have several generations. This is unusual compared to other soft scale bugs who only have one generation in a year.
According to the University of Illinois, they have several life cycles happening at once.
There will grown adults producing nymphs. At the same time, there will be nymphs in various stages, feeding on the plant.
Female brown scales reproduce through parthenogenesis. This means they reproduce without fertilization from a male scale.
The eggs stay inside the scale until they’ve hatched. Then the female’s body releases the nymphs.
Once they’re released, the nymphs crawl away from their mother to find a place to feed. Hence, the nickname “crawlers”.
The nymphs don’t get too far from their mother in the beginning.
They’ll stay in the same place to feed for the majority of their lives until they reach adulthood. This takes about a month.
If there is a male, he’ll go through the same growth stages. But once he reaches adulthood, he gets his wings.
How Brown Scales Attack Your Plant
As most indoor plant pests do, brown scales feed on the sap of a plant. But these bugs tend to feed on larger amounts of sap for their nutrients and hydration.
It provides them with everything they need to thrive and survive. It’s also what your plant needs to thrive and survive.
First, plants absorb nutrients from the soil. This is usually from the fertilizer you use on your plant.
These nutrients are carried through the plant by its’ phloem sieve tube elements.
Next, the plants absorb water from their soil. Like the nutrients, indoor plants get their water from your care too.
Xylem cells carry water through the plant. The cells distribute the water to the rest of the plant as they travel.
So, when they feed off of your plant, they’re stealing your plant’s lively hood. It can’t go through photosynthesis.
It will start to look ill because it is ill. In the worst cases, brown scales can kill your indoor plant.
On the bright side, it’s very rare for plants to die from these bugs. The infestation has to be pretty severe.
How to Prevent Brown Scale
Whenever you can, you need to prevent a brown scale infestation. Getting rid of any plant pest is frustrating. It also takes a lot of work and time.
Scale insects have become more of a problem due to climate change.
The hotter an area is, the more stressed scales become. And the more stressed they come, the more eggs they produce.
So, only a few scales on your plant can turn to many more fast.
The longer and hotter periods of heat kill the predators that take care of scales naturally.
One way to prevent brown scales is to make sure you’re watering your plants as you should already be doing. Particularly during the summer months.
It can be that simple to stop the critters from attacking it.
So, if a few scales find their way to your plant, they’re not going to be stressed from the heat. They won’t be popping out nymph after nymph after nymph.
The best way to prevent a scale infestation is to inspect every new plant you buy, before bringing it in your home. Especially if you have other plants.
It doesn’t take long for these bugs to spread out to other plants when they’re available.
When the bug’s food source is scarce or there are too many mouths feeding, they have to find somewhere else to go.
An infested new plant is the easiest way to get a brown scale infestation for all your plants.
Check your plants every day for any bugs. Always be vigilant. You’ll catch the brown scales before the number grows.
How to Get Rid of Brown Scale
Detecting Brown Scale
So, what are the signs of a brown scale infestation on your plant? There are a few things to look for to confirm your suspicions.
When brown scales steal the sap from your plant, it’ll have slow growth. If your plant has a normal growth rate, you’ll notice the difference quickly.
The next sign you’ll notice is droopy, yellowing leaves. They might even curl from a lack of nutrients. There’s also a strong possibility that the leaves will drop off.
Losing large amounts of sap weakens a plant so it’s more likely to get injured by the smallest incidents.
As the pests feed, they excrete a sugary honeydew. Undigested sugar and water make up honeydew.
This mix passes through a scale’s digestive system and passes onto the surface of a plant.
You can see honeydew residue on your plant. It’s a strange clear and sticky substance found on both the leaves and stem.
It’s a huge hint that you have a brown scale infestation or some other bug that feeds on sap.
Another way to detect brown scales is when you see a black sooty mold start growing on your plant. Honeydew left behind causes the mold.
The spores from this black mold can spread fast to other parts of your plant.
The mold makes your plant sick and it cuts down on the surfaces for your plant to go through photosynthesis.
If your plant has one of these symptoms or more, you should try to get a visual confirmation. This can be hard to do when it comes to brown scales since they’re so small.
The bugs look like strange brown bumps on your leaves. They can be on top of a leaf or underneath a leaf.
You’ll also find them on the stem of your plant feeding. You can find them even feeding on branches if your plant has branches.
Small Brown Scale Infestations
When you catch a brown scale infestation early, taking care of the problem isn’t quite as hard.
Your first option for getting rid of a small infestation is to pick them off one by one. You can also rub them off of the leaves.
You need a strong stomach to do it this way. They’re very creepy-looking creatures, even for bugs.
Another method is to use ethanol alcohol. You can use 70% isopropyl alcohol too.
Since brown scales can be difficult to get rid of, we prefer to use stronger alcohol.
But you should test a small area of your plant before using alcohol. It’s strong and some plants can’t take it. Let the plant sit for a day and see how it did.
If it’s too strong, use the isopropyl alcohol instead. Again, you’ll still want to test a small area to make sure your plant doesn’t have a bad reaction.
You can always dilute the isopropyl alcohol if you’re worried about any damage to your plant.
You’ll need either a cotton swab or cotton ball for this method. You’re going to dab an end of the cotton swab with the alcohol. Or dab the cotton ball with it.
You’re going to dab all the infested areas with the alcohol. This should kill the brown scales.
Neem oil is also a fantastic way to get rid of small brown scale infestations. It’s all-natural. Plus, it doesn’t leave gross residue behind on your plant when you use it.
You can also use neem oil on large infestations but when it comes to scales, it can be difficult.
Neem oil comes from the neem tree. You can find these trees in countries like Bangladesh, India, Pakistan, and Sri Lanka.
Sometimes companies advertise neem oil as leaf shine.
You mix neem oil with water in a spray bottle. Then you can spray your plant. Make sure you spray every little bit of the plant you’re treating.
When you spray the neem oil, it hits the brown scales feeding off the plant. Since it’s oil, it’s heavy. It clogs the scales’ pores, suffocating them.
Once they’re dead, they’re easy to sweep or rub off the plant.
Dead brown scales are hollow. That soft waxy coat sometimes even rubs off when you try to grab them.
If you rub a living scale, there will be a sticky residue left on your hand or fingers.
You’ll have to repeat this method at least once a week for two or three weeks to ensure you get every single bug.
Large Brown Scale Infestations
Large brown scale infestations can be difficult to get rid of, more so than most other types of plant pests.
Horticulture oils are an option to get rid of brown scales. They’re also known as superior oils and all-season oils.
The bugs have to be in direct contact with the oil.
They kill the scales because they block the openings the scales need to breathe. They suffocate them, killing them due to a lack of oxygen.
If it doesn’t suffocate them, it will affect their feeding. When they’re not getting the nutrients they need, they’ll die.
The best temperatures for applying oils is between 45F (7.2C) and 70F (21C).
You have to mix these oils with water to dilute them. You’ll mix them in a spray bottle.
You spray all the plant with the horticulture oils, making sure you drench the brown scales.
Like with most treatments, you’ll have to repeat this process more than once. You should treat your plant with the oil once a week for two to three weeks.
Horticulture oils won’t leave a residue on your plant. The oils dissolve not long after they hit it.
One method is to use insecticidal soap. It’s one of the safest pesticides you can use on a plant. It’s not toxic so it’s not going to damage your plant.
Insecticidal soap is made from fatty acids. These fatty acids tear the membrane of the brown scale’s cells down, causing suffocation.
It removes the waxy covering on a soft scale, dehydrating the bugs as well.
Before you apply insecticidal soap to your plant, test a small area to see how it reacts to the soap. Let the plant sit for 24 hours and see how it reacts.
The soap isn’t too harsh. In most cases, it’s fine to use. But there are a few plants that are sensitive to insecticidal soap.
You need to mix the soap with water in a spray bottle. This mix should be one tablespoon for every quart of water.
The best time to use the soap is either in the morning or at night. Heat stresses a plant out. A stressed plant is more sensitive to everything.
The leaves of your plant can burn from the oil when the plant feels stressed.
The heat also slows down the oils dissolving, so it sits there on the plant for longer than it should.
You’re going to spray the plant everywhere. Don’t forget to spray under the leaves, where a lot of the brown scales hide.
The bugs need to be in direct contact with the soap for it to have any effect. So, you’ll have to spray down your plant a few more times. Every four days works the best.
The most effective method of ridding your plant of these bugs is a little mix you can make at home.
- Mild dish detergent
- Spray bottle
You’re going to mix the mild dish detergent with water. Try not to use hard water when you’re making this mixture.
For every gallon of water you use, you’ll mix in three teaspoons of dish detergent.
Once you mix the dish detergent and water in a spray bottle, you can spray your plant down.
It slows down the brown scales and suffocates them. You’ll have to wipe down the plant later on so the detergent isn’t sitting on it for too long.
Sometimes you have to turn to chemical pesticides since brown scales are difficult.
It should always be a last resort because chemical pesticides can harm your plant. Make sure whatever pesticides you use are made for indoor plants.
When an infestation is too bad, you might have to get rid of the plant.
Brown Scale Frequently Asked Questions
Why do I have both brown scale bugs and ants?
The honeydew that brown scales excrete after feeding doesn’t only create mold. Its sweetness attracts ants. Once they realize they have a steady flow of honeydew, they stick around.
What does “soft” brown scale mean?
There are soft scales and armored scales. Armored scales have an armor-like shell over their bodies. When the pest is a soft scale, it doesn’t have that armor to protect it but instead, it has a thin waxy layer.
Why isn’t the insecticidal soap killing the brown scales on my plant?
One of the most common reasons deals with the water you use when mixing the soap. You don’t want to use hard water. Hard water contains calcium and magnesium which breaks apart the fatty acids.
Soft brown scales are nasty creatures. It’s important to get rid of them before the infestation grows. It’s a process treating your plants for brown scales. But with some hard work, you’ll be rid of these bugs in no time.
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