Do Scale Insects on Plants Bite Humans?

A swarm of scale insects on your plant can be a hair-raising sight. Those scaly, armored little pests, who love attaching themselves to leaves and stems, are known to inflict harm on plants by sucking out their sap. Can they harm humans too?

Scale insects on plants do not harm or bite humans. Their mouthparts are adapted explicitly for piercing and sucking. They are not poisonous either, so there is little they can do to harm us humans, except probably to cause some allergic reactions to those sensitive to insects.

We will talk about why scale insects are not capable of biting humans and how much damage they can inflict on your plants. I will then offer tips on how to efficiently and safely rid your plants of these parasitic pests so your plants can recover quickly. Let’s start!

Why Scale Insects Can’t Bite Humans

Scale insects can’t bite humans because their mouths are incapable of doing so. Female scale insects hardly ever move when they feed on plants by first piercing the leaves or stems, then sucking the nutritious juices out. Male scale insects do not even feed. They die within 2-3 days of emergence.

Signs That Your Plants Have Scale Insects

They’re pretty easy to spot if you’re worried about a possible scale infestation among your plants. Scale insects are soft-bodied but have protective shells around them, making them almost resistant to some insecticide sprays. 

These dome-shaped, scale-like coverings are what protects females throughout their adult life. You’ll also see these in tight clusters on your plants’ leaves and stems.

Female scale insects firmly attach themselves to plants while feeding. They have hearty appetites for plant sap. As they feed on sap, they secrete a sweet, sticky substance called honeydew. Apart from the scale clusters, this sticky substance will also be covering your infested plants’ leaves and stems. Honeydew produces black sooty mold, which also coats plants and hinders photosynthesis. 

Here are other signs that indicate a possible scale infestation:

Ant Infestation

Ants and scale insects have a mutually beneficial relationship. Ants feed on scale insects’ honeydew; in return, ants protect them from predators like ladybugs. If you see a massive swarm of ants near your plants, chances are there is an abundance of honeydew for them to gather as food. Start inspecting your plants’ stems and leaves – especially the undersides – for scale insects. 

Blackened Stems and Leaves

You might dismiss these black areas as indications that the leaves and stems are merely wilting. Some might even cut off the stem or leaf and call it a day, but the truth is—these black sooty molds are the by-products of honeydew. This ugly substance signifies that scale insects are ravaging your plant. 

Yellow Leaves

Leaves turning yellow may sometimes be a natural occurrence, especially if the leaves are at the lower part of the plant. This color change usually means that the plant’s oldest leaves are dying to give way to newer, healthier growth. 

However, if you notice yellow leaves at the topmost parts of your plants, or if the yellowing of leaves is becoming widespread, it might be because of scales. They rob your plant of much-needed nutrition, causing it to wilt and die gradually. 

Web-Like Patterns on Leaves

You might think that spiders have made their webs on your plants to trap insects. Take a closer look, though, because if you see tiny eggs underneath the white, waxy fibers, you’re looking at the next generation of scale insects to infest your garden. 

Female scale insects lay eggs on the leaves and stems they feed. They may even lay their young on the underside of leaves to better protect them from predators. 

How Scale Insects Damage Your Plants

Scale insects initially damage plants by sucking out their nutrient-rich sap. Sadly, the damage doesn’t end there. By depriving your plants of proper sustenance, your plants suddenly become susceptible to wilting, fungal infections, bacterial growth, and death. 

Here are some of the ways that scale insects wreak havoc on plants:


Scale insects are parasites that live on your plants’ nutrients to survive. As they suck these essential juices from your plant, it is left with an insufficient supply to support itself efficiently. 

Furthermore, the honeydew that scale insects secrete coat plants and hinder photosynthesis. Without proper photosynthesis, plants won’t be able to manufacture food to keep themselves healthy and thriving. Plants without a good supply of nutrients will eventually die.

Vulnerability to Diseases

The first thing that scale insects do when they feed on your plants is to puncture external coverings to get the nutritious juice inside. This puncturing makes plants vulnerable to various diseases. At this point, catching illnesses might be fatal for your plants since they can no longer manufacture enough nutrients to sustain and defend themselves. 

Here are some of the more common diseases that weak plants are vulnerable to:


A canker is an open wound caused by bacteria or fungus infecting your plant. You’ll know your plant has a canker if you find swollen, hollow, cracked, or dead areas on stems and leaves. These areas do not grow back, and the disease may even spread to other parts of the plant.

Some cankers are common, and plants can bounce back from them quickly. However, if a plant is not healthy and deprived of essential minerals and nutrients, it might be unable to fight off the disease. It will succumb to the condition and will eventually die. 

Leaf Spots

Leaf spots are unsightly black spots that form on leaves. The fungal spores that carry this disease are usually introduced to the plant by water. If a plant cannot fight the disease, the spots expand and turn into blotches until they cover the entire leaf. Fungal leaf spot disease can make a plant lose all its leaves, ultimately leading to its demise. 


Blight is a relatively common airborne fungal plant disease. It is prevalent in crops, particularly potatoes and tomatoes. It manifests as burn-like splotches on leaves that grow in size and eventually take over the entire foliage. 

Prevention is essential in fighting off plant blight. Thus, if your plant is weak and has been robbed of nutrients by scale insects, it probably won’t stand a chance against blight. 

Mold Formation

The black sooty mold from honeydew renders a plant defenseless against diseases. It will coat a plant’s leaves or stems and make it almost impossible for the plant to absorb energy from the sun. Without energy, the plant won’t be able to photosynthesize and manufacture food to nourish itself. Without enough sustenance, the plant will wilt and die. 

How To Fight Scale Insects on Plants 

Fighting a scale infestation might seem daunting and overwhelming, especially if you encounter a massive horde of these pests. However, getting on top of the situation as soon as possible is critical. Quick and efficient will afford your infected plants better chances of recovery.

Here are some ways to fight scale insects on your plants:

Pluck Them Off

If you’re the type who likes taking matters into your own hands, you can physically pluck the scale insects off your plant. It can be pretty satisfying to free your plant from the clutches of these parasites. You might want to wear protective gloves, especially if you’re squeamish. 

To handpick scale, follow these steps:

  1. Fill a bowl with water and dishwashing soap.
  2. Dip a cotton swab in rubbing alcohol. Depending on how severe the scale infestation is, you might have to prepare a handful of damp cotton swabs. 
  3. Wipe off the scale insects from your plant’s leaves and stems. The rubbing alcohol will weaken their grip on your plant and might even kill them on contact.
  4. Let the scale insects drop into the soapy water. The water will drown and kill them. Doing so ensures that if some of them survive the rubbing alcohol, they won’t be able to move to another plant to wreak more havoc.

Introduce Beneficial Insects

Ladybugs and parasitic wasps are some examples of beneficial insects. They prey on scale insects and other garden pests like aphids and mealybugs. You do not have to wait for these beneficial insects to come and rescue you. You can purchase large populations of these predatory insects and set them free in your garden. They will feast on the scale insects in no time. 

Insecticide Soap

Insecticidal soap has long been a favorite among gardeners and plant lovers because it is easy to make, effective, and safe. You can use it as soon as you identify scale insects in your garden. You also do not have to worry about damaging your plants or endangering your pets who may come into contact with this spray because it does not harm anything but garden pests.

Here is how to make a simple insecticide spray:

  1. Fill a jar with a quart of water. 
  2. Add 1 tablespoon (15 ml) of soap. Any kind will do, but plant lovers swear by dishwashing liquid. 
  3. Mix well. 
  4. Transfer some of the solution into a spray bottle. Spray over your plants’ leaves, stems, and even on the soil. Ensure you pay particular attention to the leaves’ undersides. 

It would be best to spray your infected plants with insecticidal soap twice a week until all pests disappear. Note that insecticidal soap does not have any residual effects. It only kills scale insects on contact. 

Neem Oil Spray

Neem oil is a natural insecticide derived from neem trees, which are native to India. They are proven effective in eliminating common garden pests like aphids, mealybugs, thrips, and scale insects. They are safe for plants, pets, and humans, too. 

The only thing you’ll have to remember is not to spray neem oil on your plants when the sun is still high in the sky. Neem oil can burn your plant’s leaves. 

You can make neem oil spray by following these steps:

  1. Fill a jar with a gallon of water.
  2. Add 2 tablespoons (30 ml) of pure neem oil.
  3. Add 2 tablespoons (30 ml) of liquid soap. This soap will act as an emulsifier for your neem oil spray.
  4. Mix until the solution is cloudy.
  5. Pour some of the neem oil solution into a spray bottle.
  6. Spray over the leaves and stems of infected plants. Spray some on the soil as well.

Neem oil has residual effects, so you can rest assured that it will continue working for you long after spraying your plants. It is best to spray neem oil solution on scale infected plants twice a week. You may also use this as a weekly preventive measure once you’ve eliminated the pests from your garden.

Final Thoughts

There is no need to fear scale insects because they cannot bite nor harm us humans. They can, however, ravage the plants we spend so much time maintaining. The key to effectively saving your plants from these pests is to catch them soon and employ the most effective methods to get rid of them for good.

Alexander Picot

Alexander Picot is the principal creator of, a website dedicated to gardening tips. Inspired by his mother’s love of gardening, Alex has a passion for taking care of plants and turning backyards into feel-good places and loves to share his experience with the rest of the world.

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