Mealybugs: how to detect, prevent & get rid of them
Indoor plants such as orchids and cacti are often the prey of mealybugs. In this article, we explain what is the best way to combat these bugs.
No one is ever happy to make the discovery of these little insects living on their beloved plants. In the following, we have summarized everything you need to know to identify and prevent mealybugs (Pseudococcidae) and which products will help to eliminate them.
Mealybugs damage and make many plants vulnerable, which is why hobby gardeners sound the alarm immediately, when they discover the presence of the tiny white animals. 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.
Mealybugs: a profile
The family of the mealybug includes about 1000 different species, of which only 65 are considered relevant plant pests in Europe. A frequently occurring representative – especially on ornamental plants – is the citrus mealybug (Planococcus citri). The female insects can reach considerable sizes of half a centimetre, whereas the males remain considerably smaller. A unique feature of the behaviour 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 tends to be discovered a lot later. Therefore, the control is often unfortunately more challenging with this species. To add to the fire, 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 later) the first small and mobile mealybugs hatch.
How to recognise mealybugs?
The family of Homoptera includes a variety of different insects, such as scale insects and aphids among others, and many of them are also pests. The mealybug is one of the representatives easily recognised for its characteristic appearance. In addition to the white waxy layer, many species also have more or less pronounced white threads on their bodies. If you find a pest on your plants that matches this description, it must inevitably be a mealybug. Like other plant lice, they suck out the energy-rich plant sap and thus weaken the afflicted plant. In addition, this species releases honeydew, on which sooty fungi can quickly develop. Furthermore, mealybugs leave behind white, greasy residues that are not a pretty sight.
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 firs can also be a target of 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, mealybugs can also be found at the root neck, especially with cacti. Unfortunately, not even the flowering garden inhabitants are safe from the mealybugs. We have a special article where we explain how to get rid of mealybugs too.
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 when buying plants such as cacti and orchids in stores. 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 on the plants. With this approach, the likelihood of a mealybug infestation occurring in the first place is greatly reduced. In the wild, however, mealybugs can spread almost unhindered, leaving the control of the mealybugs to their natural predators. These include, for example, the larvae of lacewings, which can penetrate the protective waxy layer of the mealybugs. Using lacewing larvae is a nature-friendly option of how to deal with an outbreak of mealybugs even in the house garden.
How to get rid of mealybugs?
The easiest and often the quickest method of control is to collect the pests manually. This method is very effective for small houseplants and especially for orchids. If the leaf axils are difficult to reach, a cotton bud can help reach even the hidden mealybugs. This procedure usually has to be repeated until all young mealybugs have hatched from their eggs.
Treating mealybugs with household remedies
A possible way to treat mealybugs with household items is to use methylated spirits. A one-percent solution should be used to spray the mealybugs. This solution has the ability to dissolve the waxy layer that surrounds and protects the insects, making the pests vulnerable. The methylated spirit also penetrates the body of mealybugs and inflicts damage on their insides to such an extent that they perish. If one of your indoor plants is infested with mealybugs, you should put it into a quarantine area and separate it from the rest of your indoor plants. There, the affected plants can be treated. Another method that deactivates the waxy layer of the mealybugs a mixture of water and liquid soap. Many of us use liquid soap for cleaning – but, if diluted with water, it can be used as a spray against mealybugs.
Another possible homemade way to treat unwanted mealybug visitors on your plants is to make extracts from various plants:
- Fern extract: Crush 100 g fresh fern leaves (Polypodiopsida) and put them into a litre of water. Let it simmer for an hour and then cool off. The cooled extract then needs to be strained and can be sprayed onto the affected plants afterwards.
- Oregano extract: Pour one litre of boiling water over 100 g fresh oregano (Origanum vulgare) or 10 g dried oregano. Allow the oregano to soak for at least 15 minutes before straining. Dilute the extract with water at a ratio of 3:1 before use and use it against the mealybugs in a spray bottle.
- Nettle extract: Take 200 g fresh nettle leaves (Urtica) or 20 g dried nettle leaves and crush them. Pour a litre of water over the leaves and let the mixture soak 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 fertilizer and to strengthen the plants. After the soaking time, remove the most affected plant parts and spray the rest of the plant with the undiluted extract.
- Garlic extract: Chop 50 g 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.
Regular application of these homemade extracts will certainly wipe out the mealybug infestation. If you are dealing with a more severe infestation, not even these extracts might be of help. It might be necessary to try natural or chemical ways of treatment, which are described below.
Learn about the best ten homemade remedies for pest control in the garden in this article.
Treating mealybugs naturally
Due to its shielding waxy layer, the mealybug is well sheltered from predators and from many methods of treatment as well. Many natural agents such as products with neem and preparations with the active ingredient pyrethrum cannot pervade the waxy layer. Because of that, the mealybug often survives the measures of protection unscathed. The only effective means of treatment against mealybugs are the 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 there is a significant disadvantage to it. 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.
However, there is also a natural antagonist to the mealybug. The Mealybug ladybug (Cryptolaemus montrouzieri), also 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 specializing in natural plant protection offer these special ladybirds to be bought as adult animals or larvae for application to infested plants.
Conventional methods of treatment
Of course, it is also possible to chemically control the mealybugs. Although the use of chemicals is not always the best or gentlest option of treatment there is, unfortunately, it is sometimes unavoidable. The situation calls for chemical treatment in particular if the mealybugs are targeting the root area of plants. The simplest form of application is the use of sticks containing pesticide. These are inserted into the soil. The active ingredient is slowly absorbed through the roots of the plants and, while the mealybugs feed, they ingest it. The mealybugs are thus eliminated in a short time. However, this method only works with plants that also require a relatively large amount of water. Cacti and other succulents do not need plenty of water and, for this reason, they do not take in as much of the pesticide as is needed to treat the mealybugs successfully. The most effective products are the so-called full-system insecticides. With these types of products, the active ingredient is absorbed through the leaves of the plants and released to the mealybugs in this way. Therefore, the full-system insecticides are a more effective way of getting rid of mealybugs.
Summary of mealybug treatment:
- The simplest and quickest method of combating mealybugs is to collect them, if necessary with cotton buds
- Suitable household remedies for the fight are solutions made of methylated spirits, liquid soap and plant extracts
- Paraffin oil is the only effective natural agent against mealybugs
- The Mealybug ladybirds are natural predators of mealybugs and can be used as a treatment option
- In an emergency, mealybugs can also be chemically controlled
Are mealybugs dangerous to humans?
As is probably clear by the end of this article, mealybugs can be very harmful to our indoor plants. 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.