Why Does My Cactus Have White Fuzz?

Cactus plants are an easy-to-maintain and beautiful addition to your home.

From taller plants that grow up to a height of 50 ft. to low-growing cacti, this succulent is pretty versatile and grows in a variety of forms and colors.

While cactuses are typically healthy, they do suffer from a disease or two, which steal not only their beauty but also their strength and energy.

So, if you spot white, fuzzy spots on them, this likely indicates pest infestation.

White fuzz is commonly observed in cactus species. In some cases, it is completely harmless. Cactuses such as Echinocactuses are attacked at the base.

In this case, you need to be concerned about your plant’s health because the white fuzz is a sign of mealybug infestation.

As we said, the white fuzz is not necessarily harmful. In one of the cactus species called Cephalocereus senilis, also known as “the old man cactus,” the succulent’s whole body is naturally white, with a fuzz-like texture. At first glance, it resembles cotton candy.

In this case, the white fuzz consists of modified spines, which are very long and thin.

It’s the plant’s defense mechanism that allows it to guard itself against the intense heat of the desert sun.

Now that you know what causes the white fuzz on cactuses, let’s learn a little more about these juice-sucking, tiny insects:

What Are Mealybugs?

Mealybugs are small pests that are attracted to houseplants, mainly cactuses, succulents, and a few tropical plants.

As common houseplant pests, they can cause a lot of havoc on your cactuses.

They feed on the juices of a cactus until it weakens. This stunts your plant’s growth, eventually killing it.

Take a look at the pictures online of cactuses covered in Mealybugs so that you can identify them easily.

These pests attack a new plant that was already infested with bugs or their eggs.

Since mealybugs like to migrate from one plant to another, you could be looking at mass infestation in a couple of weeks.

So, before buying a cactus from a green store, inspect the cactus carefully to ensure it does not have any bugs.

The infestation might also be a result of the environment, pets, or human beings. The sight of these bugs might gross you out.

However, the good news is that they are not harmful to humans. You don’t have to worry about mealybugs crawling on you or biting you.

Mealybugs are slow-moving, small pests that are 0.5 cm long.

The white fuzz is camouflage, under which they happily feed on the cactus.

To know how mealybugs infect your cactus, you need to understand its growth cycle:

Mealybugs live for a maximum of ten weeks. The eggs take at least two weeks to transform into nymphs.

As the sixth week begins, the nymphs mature and finally grow into adults. The short lifecycle of mealybugs is why they spread so fast indoors.

They hide in a specific spot for weeks and feed on the cactus until they multiply.

Signs of Mealybug Infestation

The most common signs of mealybug infestation include yellow leaves and twisted foliage. However, the white fuzz is a dead giveaway.

Since there are some cactus species with naturally born white fuzz, differentiating it from the infestation might be difficult. This is why you need to inspect the plant up close.

Apart from this, the surface area of the cactus will look wet or shiny, or worse.

You will see fungus or sooty mold developing on the branches; this is caused by the honeydew, which mealybugs leave behind when they feed on the cactus.

One more sign that points towards the presence of mealybugs is wet spots in the soil at the base of the cactus.

Look for them before watering your plant so that you know your cactus is infected.

Once the soil is compromised, the cactus will start to look less healthy, will turn brown or yellow, and tilt to one side.

Before mealybugs settle in, they can be viewed by the naked eye. They are identified by their lined back and dull grey color.

Mealybugs lay eggs to create a barrier of protection, which looks like cotton fluff.

Male mealybugs can fly but mostly crawl their way on the plant. This is how they are able to leave behind eggs in their wake.

If your cactus is touching foliage with other plants, the infestation will spread.

Problems That Cause Mealybugs

If you are sure that mealybugs are responsible for the white fuzz, you need to figure out the underlying issue and eliminate it.

Following are some of the factors that cause a mealybug infestation:

  • High Temperatures

Mealybugs thrive in warm temperatures. As a desert plant, cactuses have quite the strength.

Their strength is their weakness and is what makes them vulnerable to mealybugs.

In their natural habitat, this is not a problem. In a desert, the nighttime temperature is very low and sometimes even falls below 0°.

This is why cactuses in the desert don’t develop white fuzz from mealybugs, whereas indoor cactuses do.

  • Humidity

One of the biggest factors that cause a mealybug infestation is humidity.

Since cactuses love humid air, it creates the perfect environment for these bugs to start multiplying.

They first damage the cactus’s outer layer and deposit honeydew in the cuts.

  • Tissue Damage

Over-watering and over-fertilization can cause tiny lesions on the cactus’s surface.

This carves out the pathway for mealybugs to penetrate the plant’s surface.

This is why you need to make sure that you don’t need to stress out your cactus.

Sometimes, mealybugs will attack your cactus without the presence of any of these factors.

If your cactus goes from being perfectly healthy to being covered in white fuzz, you probably brought in the infestation through your fresh produce from the supermarket.

Killing Mealybugs

The methods for controlling the infestation depend on where your cactus is planted. Let’s take a look at them:

Rubbing Alcohol Solution

  • Pour one part water and three parts rubbing alcohol into a spray bottle
  • Spray a small part of your cactus with this DIY solution (If you don’t spot any damage on the plant, spray it freely all over)
  • Spray the plant once a week until you don’t see the white fuzz

Note: Do not spray rubbing alcohol on your cactus directly. This will burn your plant. This is why it is diluted with water to minimize its effects.

If you see the white fuzz turning brown, it means the solution is working.

If you don’t have rubbing alcohol available at hand, you can use Neem oil instead.

As a natural insecticide, it is great at eliminating all kinds of bug infestations.

However, use Neem oil with caution because, like rubbing alcohol, it can also burn your cactus.

Dish Soap + Neem Oil

In a spray bottle, mix Neem oil, water, and dish soap

  • Spray a small part of your cactus with this DIY solution (If you don’t spot any damage on the plant, spray it freely all over)
  • After you have sprayed every part of the plant, wait for a few minutes and then rinse your cactus with cold, clean water

The reason why this remedy is only recommended for indoor plants is that it can burn outdoor plants under sunlight. For your garden cactuses, you can try a natural remedy:

Ladybugs (Cryptolaemus Montrouzieri)

Ladybugs are a mealybug-killer. Let them invade your garden in fall and spring.

Before the sun sets, water your cactuses.

You will see the bug eaters perched on the cactus, consuming the white fuzz.

Using ladybugs only works during the initial stages of the infestation.

If the white fuzz stays after a few days, it means the infestation is severe. In this case, it is better to use a chemical insecticide.

The Last Resort

If your cactus still has the white fuzz after you have tried the DIY remedies, try cleaning it with a cotton swab. This might take hours depending on the size of your cactus, but if you are a plant-lover, this won’t seem time-consuming at all.

In the end, if push comes to shove, you can try something different. Since a cactus can tolerate very high and low temperatures, you can try heating it in an oven to 110F or placing it in the fridge overnight.

Final Thoughts

Your cactus has a higher chance of survival if you create optimal growing conditions for it.

The four main ingredients that help you achieve this is a combination of direct sunlight and shade, soil, temperature, and water.

If a few days of neglect lead to a mealybug infestation, you need to act fast so that the cactus is not too far gone.

Try the DIY remedies first, use a mild store-bought insecticide next, and finally, clean the cactus physically with a cotton bud.

If everything fails, you can keep it in the oven or fridge as a last resort.

If your cactus still doesn’t show any signs of improving, all that’s left to do is dispose of it off to prevent contaminating the other plants.