Have you found small dots that resemble cotton balls on your garden or house plants? Then you have discovered mealybugs or mealybugs. These plant suckers can cause great damage and must therefore be combated. We'll tell you how this works best in this article.
How do I recognize mealybugs and how do I fight them?
You can recognize mealybugs by cotton ball-like threads, sticky honeydew, leaf spots and stunted leaves. Fight them by isolating infected plants, spraying with soft soap and spirits or garlic and nettle decoctions, and using natural beneficial insects such as ladybirds and hoverflies.
Identifying mealybugs and mealybugs
“The” mealybug does not exist; instead, like its close relative, the scale insect, there are around 1000 different species. Around 65 are classified as plant pests in Germany, with the citrus mealybug (Planococcus citri) being particularly common. This not only prefers to attack leaves and shoots, but also likes to nest in the roots. That's why this variety is also called root louse. You can recognize them by the numerous “cotton balls” on the root neck and in the root area.
Damage and symptoms
Mealybugs are usually easy to see with the naked eye
The specific type of pest - which cannot be determined by laypeople anyway - is not important for successful control. You can recognize an infestation of all mealybugs by these symptoms:
- Lice sit under a white layer of wax with cotton ball-like threads
- are often located on the undersides of the leaves
- or in the shoot axils
- often also on the roots and root neck
- Leaf spots, stunted and curled leaves
- Leaves later dry up and fall off
- Stunting and plant death in severe infestation
- white, greasy residue on and near the plant
- sticky honeydew
The sticky residue is the sweet excretions of the pests called honeydew. These cause further problems because they attract ants and are affected by sooty mold orcolonized by black fungi. If you notice increased ant activity on certain plants, especially in garden plants, it is not unlikely that you are infested with mealybugs or other plant lice such as aphids or scale insects.
Tip
Simply wipe off sticky leaves and sooty mildew
If the leaves of plants affected by mealybugs are covered with a blackish film, this is sooty mold. This is a fungus that feeds on honeydew and only adheres superficially to leaves and shoots. Therefore, you can simply wipe the covering carefully with a cloth dipped in lukewarm water. You should do the same with the sticky residue left by the pests so that the photosynthesis of the affected plant is not disturbed.
These plants are particularly frequently affected
Mealybugs particularly like to sit on citrus plants such as a lemon or orange tree. But the pests are also often found on orchids, cacti, palm trees and other houseplants. In addition to hydrangeas, other herbaceous perennials and herbs in the garden are at risk of infestation.
He althy and strong plants can usually defend themselves, but if the plants are weakened by an unsuitable location or incorrect care, an infestation is likely. Mealybugs and mealybugs mainly occur in warm, dry weather, such as in the summer months or, on houseplants, towards the end of winter.
Fighting mealybugs effectively – what really helps?
“Why should I use toxic (and expensive!) chemicals when effective antidotes grow in the garden?”
You have various options when it comes to combating mealybugs and effective plant protection. Don't immediately resort to chemical treatment, even if it seems easier at first - toxic substances pose a whole range of subsequent problems. Instead, we have put together some tried and tested home remedies against plant suckers here.
First aid measures
With a moderate infestation, it is often enough to rinse the affected plants thoroughly at regular intervals
Once you have identified a mealybug infestation, you must isolate the affected plants - otherwise other houseplants will quickly become infected. Furthermore, these first aid measures help to counteract further spread:
- spray affected plants with a strong jet of water
- cut back severely affected plant parts
- collect isolated mealybugs, e.g. B. with the help of a toothbrush
- Unpot heavily infested plants and remove soil residue
Once these steps are completed, take further action. You can find out which ones make sense and how to use them in the following section.
Make your own spray – This is how it’s done
Easy to prepare spray treatments based on have proven to be particularly effective
- Soap and spirit
- garlic
- Fernwort
- and nettle
featured.
Soap and spirit
Almost classic in the fight against mealybugs and other pests is a spray made from liquid soft soap and denatured alcohol. This home remedy is very effective, but is not suitable for all plants. Therefore, before use, carry out a tolerance test by first applying the solution to a small area. Then wait a few hours: If the plant shows no reaction and there are no changes to the area, carry out the spray treatment. However, if spots or curls appear on the treated leaves, then it is better not to treat them.
Make the soft soap and spirit mixture as follows:
- Stir a tablespoon of liquid soft soap or dishwashing liquid
- in a little warm, lime-free water.
- Add a tablespoon of denatured alcohol.
- Caution: denatured alcohol is extremely flammable! No open fire or heat source nearby!
- Dissolve everything in a liter of soft water.
Now fill the spray into a suitable spray bottle (€7.00 on Amazon) and spray the affected plants extensively with it. Don't forget the undersides of the leaves and the leaf axils - this is where the mealybugs particularly like to sit. Alternatively, you can dip a cotton swab into the solution and dab each louse individually.
Plant broth
For many plants, especially orchids, herbal extracts based on garlic, nettle or fern are much better tolerated. You collect the last two ingredients in nature, where both are abundant. When it comes to nettles, make sure to collect leaves and stems from specimens that are about to bloom - these have the highest proportion of active ingredients.
And this is how it works:
- You need 200 grams of nettles or 100 grams of fern or garlic.
- Use whole garlic bulbs including the skin.
- Chop all parts of the plant as small as possible.
- The better the active ingredients can be removed.
- Pour hot water over the plant material.
- However, the water must no longer bubble.
- Let the brew steep for about 24 hours.
- Strain the plant parts.
- Pour the brew into a spray bottle.
Then use the product as a spray or water the affected plants with it. It is important that you carry out the treatment several times at intervals of several days. This is the only way to catch all the mealybugs, especially those that have just hatched from the eggs.
Mealybugs on the roots – what to do?
If the roots are infested with mealybugs, they should be cleaned thoroughly and potted in fresh soil
If the mealybugs are on or in the roots, pot the plant first. Afterwards
- remove any adhered substrate
- and throw this away
- clean the planter thoroughly
- and disinfect it with alcohol
- rinse the roots thoroughly in the shower
- and dip them in a garlic or nettle stock for about 15 minutes
After this treatment, place the plant in fresh substrate and keep a close eye on it. If the mealybugs appear again, repeat the treatment.
Excursus
Which biological pesticides still help?
Biological plant protection products, for example based on pyrethrum (obtained from chrysanthemums) or neem (obtained from the seeds of the Indian neem tree) reliably help against many pests, but not against mealybugs. At least that applies to products applied externally. These do not penetrate the solid protective layer under which the harmful insects sit. Instead, you can purchase special products commercially that you can simply add to the water or stick into the substrate in the form of sticks. The plant absorbs the active ingredients so that they get into the plant sap - and thus attack the mealybugs from the inside.
Take action against mealybugs and mealybugs with beneficial insects – completely naturally
Beneficial insects - i.e. useful because they are predatory insects - have proven to be very effective in combating mealybugs and other pests. But be careful: you must not use these together with plant protection products (not even those based on neem etc.!), as these also kill the beneficial insects. Help against mealybugs:
- Ladybug
- lacewings
- Parasitic wasps
- hoverflies
- Predatory Beetle
You can get the natural predators of mealybugs from specialist retailers, where the animals are sold as larvae. Use according to the package instructions provided, paying particular attention to the recommended temperature and lighting conditions. This is the only way the beneficial insects can develop as desired. After treatment, the insects disappear on their own.
In the garden, you should ensure a he althy ecological balance so that beneficial insects and other animal helpers such as bees, bumblebees, butterflies, birds and hedgehogs feel comfortable. This way you keep the pests at bay from the start. Cultivate a lot of umbelliferous plants, as these are among the preferred food plants of beneficial insects - usually only their larvae feed on a predatory diet.
Excursus
Do not scratch off mealybugs
You often read the “tip” to simply scrape off the mealybugs and mealybugs and remove them, at least in the case of a small infestation. It's better not to do that, because beneath the protective layer are not only the actual louse but also its eggs and young larvae. If you scratch the layer, you will only kill the adult louse - but you will distribute their tiny eggs and larvae unnoticed. As a result, the animals continue to multiply.
Prevent mealybugs effectively – so the pests don’t stand a chance
Too much or too little water promotes mealybug infestation
To prevent an infestation with mealybugs or other pests, these preventive measures are useful:
- Make sure each plant has optimal location conditions.
- Avoid over- or under-supply of water.
- Avoid over- or under-supply of fertilizer.
- In particular, nitrogen-based fertilization weakens the plants.
- Keep the humidity high for houseplants.
- Overwinter them - depending on the species and variety - as cool and bright as possible.
For garden plants, you can strengthen the plant's defenses by regularly spraying or watering them with nettle or horsetail decoction. You should also avoid monocultures, as they promote pest infestation. Plant neighbors such as lavender, nasturtium, savory, garlic, onions, leeks and chervil, however, keep many pests away.
Frequently asked questions
Are mealybugs also dangerous for humans?
Don't worry, mealybugs are not dangerous to people or pets. The pests feed exclusively on nutritious plant juices, which is why only garden and house plants are at risk.
Where do mealybugs come from anyway?
In most cases, you bring the pests home with newly purchased or gifted plants. Well-hidden individual specimens are not even noticeable when selecting, and plants with minor infestations often still look very he althy. However, if the conditions at home are right, the plant lice multiply explosively. A dry, warm room climate is particularly beneficial for their development.
When do mealybugs appear particularly frequently?
Mealybugs appear on houseplants all year round, but in the garden you only find them during the growing season. In winter, the pests and the plants go into hibernation; after all, no plant juices flow during the cold season. It's different with houseplants, at least if you grow them warm all year round.
Can mealybugs tolerate cold? Would it perhaps help to put the infected houseplants out on the balcony?
Unfortunately, mealybugs and scale insects are quite insensitive to climatic changes. They occur in both dry and humid indoor air and can even tolerate frosty temperatures. Therefore, it makes no sense to put infected houseplants on the balcony in winter - the pests will definitely survive the cold shock. Only your plants will die, as most exotic plants come from the tropics or subtropics and are therefore not frost hardy. During the summer months, however, it can be an advantage to put infected plants outside - this makes control easier.
Can mealybugs actually fly?
Mealybugs can actually fly, but they are usually only males. They are externally similar to the whitefly, so confusion is sometimes possible. The male mealybugs and mealybugs die after mating, while the females build a protective cocoon and thus become immobile. But be careful: these pests can reproduce through virginity; fertilization is not necessary!
Tip
Paraffin oil, which you apply directly to the mealybugs with a swab, is also worth a try. You can then carefully remove them.