Mealybugs: how to detect, prevent & get rid of them
Indoor plants such as orchids and cacti are frequently infested by mealybugs. Keep on reading to find out the best way to combat mealybugs.
No person will be happy to discover these little insects living on their beloved plants. In the following, we summarised everything you need to know to recognise and prevent mealybugs (Pseudococcidae) and which products help to eliminate them.
Mealybugs thrive in warm and humid climates which is why they can often be found indoors such as in your living room or glasshouse. They reproduce faster and cause immense damage to your plants. But don’t worry, with our tips and tricks you will quickly get the situation under control and your plants will survive the mealybug attack unharmed. Between mealybugs also occur outside – for example on beech, apple or maple trees. The possible damage is much lower though than indoors.
Mealybugs: a profile
The family of the mealybugs includes about 1000 different species. A commonly known species – especially on ornamental plants – is the citrus mealybug (Planococcus citri). The female insects can get as big as half a centimetre, whereas the males remain a lot smaller. A unique trademark of this species is that some of them live in the root area of plants. Because of that, the infestation is not that apparent and takes longer to discover which makes it more challenging to control this species. What is more, the citrus mealybug also reproduces rapidly. Adult females lay many hundreds of eggs, which are protected by a waxy layer. After two days (sometimes a little more) the first small mealybugs hatch ready to go.
How to recognise mealybugs?
The family of Homoptera includes a variety of different insects, such as scale insects and aphids, many of them classified as pests. The mealybug is one of the easy to recognise species due to its characteristic appearance. That being a white waxy layer and with many mealybug species also more or less pronounced white threads on their bodies. If you find a pest on your plant that matches this description, it is very likely to be a mealybug. Like other plant lice, they suck out the high-energy plant sap and thus weaken the afflicted plant. In addition, this species releases honeydew, which is prone to sooty mould fungi. This will disturb the process of photosynthesis of the plant. Another typical feature of mealybugs are white, greasy residues.
Especially houseplants like succulents, cacti and orchids are a favourite of the mealybug. However, trees growing outside in the open air such as apple trees or Douglas fir can also get infested by various species of mealybugs. Identifying the culprits is very easy, though. The insects are coated with a white layer of wax-like substance and hide under the leaves or in leaf axils. Occasionally, they can also be found at the root neck, especially with cacti. Unfortunately, not even the flowering garden inhabitants are safe from the mealybugs.
How to prevent mealybug infestations?
Mealybugs are often introduced via infested indoor plants. For this reason, you should always take a close look at the plant already when buying it – especially with cacti and orchids. If some of the plants in the store are infested, you should also keep your hands off the other plants there. Although you might not see them, there may already be eggs inside. Outdoors mealybugs spread unconstrained, only controlled by their natural predators. These include, for example, the larvae of lacewings, which can penetrate the protective waxy layer of mealybugs. For this reason, we generally recommend cultivating your house garden in a manner that is gentle on beneficial organisms.
Tip: Adult lacewings mainly feed on pollen, nectar and honeydew. Thus, you will find them wherever flowers and aphids can be found. Creating a flower patch as habitat for aphids and especially lacewings protects your entire home garden, because that way hungry lacewing larvae are always present when mealybugs want to attack your ornamental plants or fruit trees. How to get rid of mealybugs?
If you have mealybugs inside your house, you should make an effort to combat them. They do not only weaken the plants but also transmit fungi and plant viruses. As soon as you notice an infected plant, set it aside from your other plants creating a quarantine distance. Then you can start applying measures to control the infestation without putting your other plants at risk of infection.
Treating mealybugs naturally
Paraffin oil: Another effective method against mealybugs are products based on paraffin oil. Paraffin oil coats the mealybugs with a thin film of oil and suffocates them. Paraffin oil is extremely effective but bears a significant disadvantage: Not all plants tolerate it. For this reason, you should always try the treatment on a small part of the plant first. In addition, paraffin products must never be used in direct sunlight, otherwise the plant can suffer burns.
Beneficial organisms: There are also natural antagonists for mealybugs. The mealybug ladybug (Cryptolaemus montrouzieri), fittingly referred to as mealybug destroyer, is a black to reddish brown beneficial insect. The white larvae of this ladybug species exterminate large quantities of mealybugs. Companies specialising in natural plant protection offer these special ladybirds to be bought as adult animals or larvae for application to infested plants.
Tip: Do not use sprays or other house remedies when applying beneficial organisms. They may not only harm the mealybugs but also your beneficial organisms which would be counterproductive.
Collecting: The easiest and often the quickest method for mealybug control is to collect them manually. This method is effective for small houseplants and especially for orchids. If the leaf axils are difficult to reach, a cotton swab can help reach even the hidden mealybugs. Repeat the procedure regularly until all young mealybugs have hatched from their eggs.
Methylated spirit: Another household remedy against mealybugs is methylated spirit. Spray a one-percent solution (10ml of spirit for 1 litre of water) on the infested plant. The solution will dissolve the waxy layer that surrounds and protects the insects, making the pests vulnerable. The methylated spirit penetrates the insects and they perish.
Soapy spray: The waxy layer of mealybugs is also destroyed by soft soap. Many of us use liquid soap for cleaning – but, if diluted with water, it can be used as a spray against mealybugs.
Extracts and teas: You can also prepare extracts or teas to combat the unwanted visitors while at the same time strengthening your plants. Try the following:
- Oregano tea: Pour a litre of boiling water on 100g of fresh oregano (Origanum vulgare) or 10g of dried oregano. Let it steep for at least 15 minutes before straining. Dilute the extract with cold water at a ratio of 3:1 before using spray onto the mealybugs.
- Garlic broth: Chop 50 g of fresh garlic (Allium sativum) and pour one and a half litres of boiling water over it. This mixture should soak for about half an hour and then strained. After it is cooled, the garlic extract can be sprayed onto the affected plants.
- Nettle extract: Take 200g of fresh nettle leaves (Urtica) or 20g of dried nettle leaves and crush them. Pour a litre of water over the leaves and let the mixture steep for about eight hours. If the extract is to be used against mealybugs, it should not ferment. If it does start to ferment, you can still use this mixture as a fertiliser to strengthen the plants. After steeping, remove the most affected plant parts and spray the rest of the plant with the undiluted extract.
You can apply the extracts above several times to combat the mealybug infestation effectively. For our household remedies for outside read more in this article. If you are dealing with a more severe infestation, the remedies mentioned above may take too much time before they show effect. Therefore you might also want to consider using conventional treatment, as described below.
Conventional methods of treatment
Of course, it is also possible to control the mealybugs chemically. Although the use of chemicals is not an ideal or the most gentle option of treatment it may unfortunately, sometimes be unavoidable. In particular, a situation calls for chemical treatment if the mealybugs are targeting the roots of your plants. The most simple form of pest control is sticks containing pesticide. Insert them into the soil. The roots will slowly absorb the active ingredient and pass it on to the feeding mealybugs.
Tip: This method only works with plants that require a large amount of water. Cacti and other succulents do not take in as much of the pesticide as is needed to treat the mealybugs successfully.
The most effective products are so-called systemic insecticides. The active ingredient is absorbed by the leaves of the plants and that way released to the mealybugs. Although this is an effective method against mealybugs, keep in mind that it will also kill other insects and may also be harmful for you as you use it. Therefore, protect yourself when applying the chemicals and strictly adhere to the instructions of the manufacturer.
Summary of mealybug treatment:
- The most simple and quick method of combating mealybugs is to collect them, if necessary with cotton swabs
- Suitable household remedies include solutions made of methylated spirits, liquid soap or plant extracts
- Paraffin oil is the only effective natural agent against mealybugs
- Mealybug ladybirds are natural predators and can be used as an option for treatment
- In an emergency, mealybugs can also be controlled chemically
Are mealybugs harmful to humans?
As is probably clear by the end of this article, mealybugs can be very harmful to our houseplants. However, we do not have to worry about our own health. Mealybugs are only dangerous to our green leafy roommates, but pose no threat whatsoever to us. Therefore, treat the plants without hesitation and keep them in your living rooms.
Mealybugs can cause (great) damage to indoor plants and are tedious to get rid of. However, you do not have to worry about your health as the pests are not harmful to humans. You can treat your plants without hesitation and keep them in your living space. Also possible plant viruses transmitted by mealybugs are not passed over to humans, since plant cells and animal cells are very different.
Did you just ward off a mealybug infestation and now your plants need recovery to return to new beauty? In this article we will show you how to fertilise your houseplants in the best way possible to help them regain health and vitality and prevent new pest infestations.