How to get rid of scale insects?

Article for :All parent plants

Mealybugs are like those songs that stick in your head. Once they're there, they're hard to get rid of. But here are a few methods to help you get rid of them (not Bad Romance or Can't Get You Out of My Head, we haven't found a solution to that yet).

How to recognize mealybugs?

Mealybugs in close-up and in action - Photo by It-management / Wikipedia

The cochineal is an insect belonging to the Coccoidea family. There are over 8,000 different varieties. The ones most frequently found on our houseplants and in our gardens are :

Mealybugs (Pseudococcines);
Carapace scale insects (Lecanines);
Shield mealybugs (Diaspines).

Mealybugs vary in appearance from one species to another, and between males and females. They measure 1.5 centimetres at best, and may be covered with a white (mealybugs) or brown (shield or carapace scale) carapace.

The presence of scale insects on plants is easy to spot. As well as insects, you'll find a white, sticky, cottony substance on leaves and branches. This is the honeydew secreted by these undesirable hosts.

Are mealybugs dangerous for my plants?

On this hibiscus, we have the winning combo: discoloration, honeydew and insects - Photo by Scot Nelson / Flickr

Mealybugs are a danger. They are sucking, biting insects. They suck the sap from plants and slow down their growth. If you do nothing, or if the infestation is too heavy, the plant will eventually die.

Before killing your plant, parasites will cause :

Slower flowering and fruiting;
Discoloration of foliage;
Deformation of new leaves;
The appearance of fumaginia (black fungus) on the leaf blades.

Scale insects spare no one. They like to invade vegetable crops, houseplants, fruit trees... They are particularly common on :

Cacti and succulents Aloe vera, Euphorbia trigona);
Citrus trees Lemon tree, Orange, Mandarin);
Orchids;
Ficus.

These insects can be found both indoors and outdoors. However, they prefer warm, humid environments. Mealybugs are therefore most active indoors or in the garden in summer. In winter, however, they are rarely seen outdoors. They can't stand the cold.

Preventing the appearance of mealybugs

Fresh air helps prevent the appearance of mealybugs - Photo by José Santarém / Pexels

We're not going to lie to you: getting rid of mealybugs is no easy task. So it's better to be safe than sorry.

Check plants when you buy them

Mealybugs are mobile. When you buy a new plant, examine it to make sure it's not infected. Quarantine it for three to four weeks, even if there are no signs of infection. Larvae can take several days to develop. This way, you can be sure that your latest acquisition won't contaminate the rest of your jungle.

Aerate

Mealybugs like confined environments. When indoors, ventilate regularly to renew the air and prevent their proliferation. In summer, take your plants outside to the garden, terrace or even windowsill.

Adopt the right growing conditions

Healthy plants are less vulnerable to attack by biting and sucking insects such as mealybugs. Give your plant sufficient light and adapt watering to its needs. If you find it hard to be regular, download the Monstera app. You'll be notified when it's time to water.

Natural, effective treatments to get rid of scale insects

As well as being effective against mealybugs, the Australian ladybug is adorable - Photo by Holger Casselmann / Wikipedia

So you've decided to save your plant? You'll have to be patient and give it your all. Controlling mealybugs is tedious, and you rarely get results on the first try. Don't hesitate to repeat treatments several times if they don't work the first time.

Prune

Regardless of the treatment you're going to inflict on the unfortunate plant, we recommend that you start by pruning. Remove honeydew-covered leaves and prune the most affected branches. This is an effective way of reducing the infestation. Pruning is also good for plants. It enables them to grow better.

The aim of pruning is to limit the proliferation of insects, not to allow them to spread. So :

Clean your pruning shears before and after pruning;
Don't compost plant waste.

You can burn the infested parts or dispose of them at the waste collection center (or green waste collection). Professional plant recycling techniques destroy mealybugs.

Remove, collect

You can also remove the insects. Using your fingers or a toothbrush, remove and crush them. This method can reduce the infestation, or even put an end to it if you're in the early stages. But it's rarely enough on its own. In fact, you can't remove the eggs and mealybugs buried in the substrate.

Water

If the attack is in its early stages and only a few leaves are affected, crush the mealybugs and give your plant a shower. Remember to wrap the pot in a plastic bag to avoid wetting the soil. This way, the larvae won't land in the substrate and you won't risk over-watering.

Keep an eye on your plant for the next few days. At the slightest sign of relapse, repeat the operation or try another of these methods.

Alcohol

If mealybugs don't like water, they don't like alcohol either. For small, localized infestations, soak a cotton swab in methylated spirits or 90° alcohol and wipe over the infected areas. The alcohol will kill the insects and drive them away.

Black soap, vinegar, alcohol - any way you can!

When the invasion has reached the whole plant and you see honeydew, water and alcohol won't help. There are a number of tried-and-tested recipes, even if the results are uncertain. For example, you can mix :

1 liter of water and a tablespoon of black soap;
1 liter of water, a spoonful of black soap and a spoonful of white vinegar.

Spray this mixture on your plant every day, morning and evening, until the insects disappear. The black soap should destroy the cochineal shells, while the acidity of the vinegar kills them.

Not working? Try another recipe by mixing:

500 ml water ;
2 tablespoons black soap ;
2 tablespoons white vinegar.

Apply the mixture to the affected areas and leave for an hour. Rinse with clean water.

Once the mealybug infestation has been brought under control, repot your plant to make sure the soil is free of eggs and larvae.

Biological control

Biological control involves inviting auxiliary insects onto your plant, as they are the natural predators of mealybugs. They will take care of the unwanted insects in just a few weeks. There are several species that can control mealybugs, such as :

Lacewing larvae;
Nematodes;
Australian ladybugs (Cryptolaemus montrouzieri).

These species are particularly effective against mealybugs. With other types of mealybug, results are weaker or non-existent.

To buy beneficial insects, go online. Several online stores offer to send nematodes, ladybugs or lacewings to your home.

Is coffee grounds effective against mealybugs?

Coffee grounds have no effect on mealybugs, either as a repellent or as an insecticide. If you're looking for a natural solution to control biting and sucking insects, it's best to stick to black soap, commercial organic insecticides or biological pest control.

By Servane Nemetz
on 09-09-2025 at 20h35