Mealybugs - recognize and fight them naturally

the essentials in brief

Mealybugs often hide themselves and their eggs in the substrate, in the leaf shells or axils. They are often difficult to spot in the early stages of an infestation.
The pests protect themselves and their offspring with a layer of wax, which is why many biological control measures do not or hardly work.
(Homemade) pesticides based on paraffin oil or alcohol are very suitable for effective control, but not all plant species can tolerate them. Orchids in particular are very sensitive.
Some beneficial insects such as lacewing larvae or parasitic wasps (€ 14.59 on Amazon *) as well as a bright location and high humidity (especially during the heating season in winter!) Help against mealybugs and mealybugs.

Recognize mealybugs

Mealybugs, often referred to as mealybugs or root lice, are stubborn and difficult to control plant pests. They suck on all parts of a plant to get their nutritious sap. In doing so, they not only excrete honeydew, but also toxins that add to the infested plants. The adult animals are surrounded by a waxy layer that protects them from enemies and harmful environmental influences. But not only this makes effective control difficult, but also the rapid reproduction rate and resourceful survival strategies.

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Not only do mealybugs like to hide their eggs in places where they are difficult to find - for example in the leaf axils, in bracts or in the substrate - they are also able to withdraw when living conditions deteriorate and wait for better times. So don't lull yourself too quickly after countermeasures that are supposed to have been successful: Often the animals reappear after a few months of rest and spread again en masse.

Appearance

As long as an infestation with mealybugs is still in the initial phase, it is not easy to recognize. However, the animals have a very distinctive appearance, which is why you cannot confuse them. And this is what the pests look like:

between one and twelve millimeters in size
white, pink or light brown in color
covered by a white layer of wax
on this there are whitish threads
reminiscent of small cotton balls

Basically, both the adult animals and their eggs and larvae are found on all parts of the plant. Mealybugs not only sit on the leaves, but also on (soft) shoots and stems, on leaf axils and even on the roots - here they are of course particularly difficult to find.

Damage

In contrast, the damage to infested plants caused by mealybugs is much less specific. In principle, these can also come from other pests, whereby one and the same plant can of course also be colonized by different types of plant pests. You can tell that something is absolutely not right and you need to act urgently by these symptoms:

Leaves roll up
Leaves turn yellow and fall off
sticky coating on leaves and other parts of plants
this can also drip onto the surface
whitish webs on leaves and other parts of plants
whitish smear on the inside of plant pots if roots are attacked

The sticky, often dripping coating is called honeydew, which is excreted by the mealybugs (and other plant pests as well). Honeydew, in turn, forms the ideal basis for the settlement of sooty fungi, which often appear as a result of pest infestation. The infected parts of the plant then look as if they were covered with a black smear.

Feces and fungi should always be wiped off as they hinder photosynthesis of the plant and thus its growth

Digression

Why it is so important to combat a mealybug infestation early on

Since mealybugs multiply extremely quickly and the animals are not very particular about their host, the infestation is not limited to one plant. Instead, the infection quickly spreads to other growths, which are then also severely weakened. If effective countermeasures do not take effect in time, an infected plant usually dies quickly.

Which plants are particularly at risk?

Basically all plants can be attacked by mealybugs. Particularly popular with stubborn pests, however, are hard-leaved plants, especially if they are cultivated in the apartment - the living conditions are ideal here, especially during the winter months. But the animals can also be found outdoors, but more often in the hot and dry summer months.

However, the following plant species are particularly often affected:

Houseplants	Garden plants
Aloe vera (aloe vera)	Apple tree (Malus domestica)
Weeping fig (Ficus benjamina)	Bamboo (various)
Elephant foot (Beaucarnea recurvata)	Boxwood (Buxus sempervirens)
Money tree (Crassula ovata)	Hydrangea
Rubber tree (Ficus elastica)	Oleander (Nerium oleander)
Cacti (various)	Olive tree (Olea europaea)
Orchids (various)	Lemon tree (Citrus × limon)
Yucca palm / palm lily (Yucca elephantipes)
Poinsettia (Euphorbia pulcherrima)

Digression

Why is a mealybug infestation so common on orchids?

Orchids are particularly often affected by mealybug infestations. This is primarily due to the fact that these popular exotic species are quite demanding in their care, depending on the species and variety. To protect the flowering plants from infestation, care for and fertilize them properly and, above all, ensure an optimally bright location with appropriate temperatures and high humidity. By the way: Most of the time, you drag the mealybug infestation into your house with already infected plants.

What helps? Combat mealybugs effectively

"Know your enemy ... then you will defeat him!"

Since mealybugs are so stubborn, it is not enough to apply a spray once. Instead, in order to be ultimately (and not only temporarily) successful, you should combine several methods and be one thing in front of one: perseverance! Regularly collecting discovered animals is particularly important, whereby a slightly moistened cotton swab will be of great use to you, especially in difficult-to-reach areas such as leaf axils. It also makes sense to wipe leaves and other parts of the plant with a damp cloth - baby wipes are ideal for this purpose.

Also, be sure to take these steps:

Isolate the infected plant.
Put them in a cool and light place as possible.
Both are of course only possible with potted plants.
Clean the infected parts of the plant and collect the mealybugs.
If the infestation is too strong, cut back the plant (heavily).
Repot the plant in fresh, sterilized substrate.

Suitable home remedies

A classic home remedy for mealybugs is denatured alcohol. Of course, you don't use this pure - unless you want to treat an infected cactus - but mix a solution of water, soft soap (€ 17.27 at Amazon *) and alcohol. For this you need:

one liter of water
15 milliliters of denatured alcohol
15 milliliters of soft soap or paraffin oil

Mix all of the ingredients together and spray the infested plants about every two days. Sensitive plants such as orchids, however, should not be sprayed, instead brush the mixture directly onto the affected parts of the plant. Denatured alcohol is so well suited to combating mealybugs because it softens the protective wax shell and thus makes the animals vulnerable. In addition, the agent penetrates the body and lets the pests die off.

However, some of the plant extracts produced in-house are also effective against mealybugs and at the same time offer the advantage of fertilizing the plants treated with them and strengthening their defense system. These preparations are particularly suitable against mealybugs and mealybugs:

Suitable plant	preparation	application
bracken	Simmer 100 grams of fresh leaves in one liter of water for an hour	Let the tea cool down, strain and spray the plants undiluted with the brew
oregano	Pour 100 grams of fresh oregano herb or 10 grams of dry oregano with a liter of boiling water and let it steep for at least 15 minutes	Let cool, strain (if necessary) and dilute 1: 3 with water, spray plants
Nettles	Pour one liter of water over 200 grams of fresh nettle leaves (from non-flowering plants!) And let it steep for eight hours	strain and spray plants undiluted
garlic	Chop 50 grams of fresh clove of garlic, pour a liter of boiling water over it and let it steep for at least half an hour	strain, spray plants undiluted

During preparation, make sure to cut or chop the plant parts used as small as possible - the easier it is to dissolve the ingredients that are supposed to drive the mealybugs away. Spray the infected plants several times at intervals of no more than two days so that this measure is successful. However, you will only be successful with such herbal pesticides if the infestation is beginning or moderate. If, on the other hand, the mealybugs have already spread strongly, more stringent methods make sense.

How to rid the roots of mealybugs

If the mealybugs are hiding in the roots, however, you must proceed as follows:

Pot out the infected plant.
Carefully remove the substrate from the root system.
Rinse it off with a strong jet of water (e.g. in the shower).
Clean and disinfect the planter.
High-proof alcohol, for example, is suitable for this.
Alternatively, you can take a new pot and throw away the old one.
Disinfect the fresh substrate in the oven or in the microwave (instructions: see below).
Pot the plant into the fresh and disinfected substrate.
Pour them carefully, for example with nettle tea.

The procedure described is not only useful for root lice, but also for general mealybugs. You can safely assume that animals and eggs are also in the substrate as soon as the pests appear anywhere on a plant.

Fighting mealybugs naturally - biological antidotes

Biological sprays and pesticides - for example neem oil or preparations based on the natural active ingredient pyrethrum are not suitable as a control measure for mealybugs. The reason for this is the hard wax layer that protects the animals from such influences - the remedies that are otherwise so successful with other pests fail miserably here. Only the already described use of alcohol and soft soap or paraffin oil is actually effective, because these agents soften the wax and can kill the lice.

However, alcohol as well as paraffin and soft soap have a significant disadvantage: Not all plants tolerate treatment with it, but even die afterwards. Therefore, always try out an insert on a small leaf or the like first and see how your plant reacts to it. In addition, make sure not to use the home remedy in direct sunlight - this would result in unsightly stains due to burns.

Beneficial insects against mealybugs

However, pests such as the annoying mealybugs can also be combated in other, completely non-toxic ways: The animals have many predators who are only too happy to eat eggs, larvae and adult lice and thus contain the infestation in a completely natural way. However, there are some important tips to consider when using so-called beneficial insects so that this method is successful:

do not use insecticides and other toxins at the same time
these also kill the beneficial insects
at best, refrain from using such agents six weeks before use
Use beneficial insects as early as possible
if the infestation is severe, the beneficial insects cannot keep up with eating
then first apply a beneficial agent-friendly agent (e.g. based on rapeseed oil)
only then use beneficial insects
Pay close attention to the manufacturer's instructions regarding the amount to be applied, the ambient temperature and the humidity

Particularly when it comes to the required number of beneficial insects, it is important to carefully consider and weigh up: If you use fewer of these animals, they will not be able to fight the mealybug plague. However, if there are too many animals on one plant, they tend to eat each other instead of attacking the pest larvae.

The following beneficial insects in particular have mealybugs (and other common pests!) On their menu.

Australian ladybird : particularly effective against mealybugs - only 25 of these animals eat all mealybugs on an area of up to 13 square meters, can only be used in closed rooms and from an ambient temperature of 20 ° C; Adult beetles are delivered, which are released directly on the infested plants, keeping windows and doors closed (risk of migration!), spraying plants regularly with water, as ladybugs need drinking water
Lacewing larvae : devour mealybugs between the second and third larval stage, then pupate and fly out of the apartment on their own as adults, are supplied by internet retailers in the first larval stage, repeated use makes sense
Parasitic wasps : Art Leptomastix dactylopii specializes in mealybugs, application can also be used together similar to the Australian ladybug, both types

Ichneumon wasps and ladybugs have in common that both are only active in warm surroundings. If the temperature is permanently below 15 ° C, the use of lacewing larvae makes more sense. You can get them to lay their eggs again by placing a flat bowl of honey or sugar water on the windowsill. In this way, you ensure that there are more beneficial offspring yourself, which in turn keeps the mealybugs in check.

Beneficial insects in the garden

In addition, the targeted use of beneficial insects in closed rooms - such as those in the home, in the winter garden or in the greenhouse - is more effective than in the garden, where the animals can migrate. However, such a garden can be designed in a beneficial way so that it attracts lacewings, parasitic wasps, ladybugs and the like and in this way preserves the ecological balance. Many useful insects in the garden also have the advantage that pests have no chance of spreading.

The little animals feel at home in gardens with many native flowering plants, where they can find food in abundance. Flowering hedges, wild plants such as yarrow, chamomile and corn poppy and umbelliferous plants are particularly attractive. Furthermore, you can provide the beneficial insects with a strategically sensible set up insect hotel (€ 8.87 at Amazon *) as well as one or the other sticks or piles of sticks and nesting and wintering places.

If nothing else helps - take chemical action against mealybugs

Home remedies and beneficial insects are not always sufficient to combat mealybugs. If the pests have already spread too much, for example in the roots and if the plant is already covered with them, then sometimes only the chemical club can help. Some preparations are available in specialist shops and on the Internet, which are usually incorporated into the substrate as sticks or granules and thus get into the plant via the roots. They are uncomplicated to use and also very suitable for indoor use - after all, this way the toxins do not go into the air.

However, this method only works with plants that have a high demand for water - succulents such as rubber trees or cacti take in too little water and therefore too little of the active ingredient. Therefore you have to resort to pesticides here. When using it, make sure to keep the recommended minimum distance and don't forget all parts of the plant - including the undersides of the leaves and the leaf axils! - to treat. In addition, the agent has to be injected several times, as the eggs are not killed and larvae will hatch after treatment.

video: Youtube

Various insecticides are approved and commercially available for home and hobby use. They usually contain one of the following active ingredients:

Dimethoate
Imidacloprid
Paraffin oil
Pyrethrins and rapeseed oil
Thiacloprid

Digression

Disinfect new potting soil

Since the mealybugs are often brought into the house through substrate infected with eggs, you should disinfect this if possible and thus render the eggs harmless. To do this, pack the soil in portions at around 600 to 800 watts for five minutes in the microwave or at 200 ° C for 20 minutes in the oven, spread out flat on a baking sheet. However, the disadvantage of this method is that useful microorganisms are destroyed at the same time.

frequently asked Questions

What are the causes of an infestation with mealybugs?

Mealybugs are particularly common during the heating season, as they feel particularly comfortable in dry and warm air. For this reason, it makes sense in winter to keep the air moist with a room humidifier or simply by regularly spraying the indoor plants. Also highly nitrogen-based fertilization - especially in the winter months! - promotes an infestation, as this weakens the plants and leaves them vulnerable. Avoid overfertilizing, as such plants are more likely to be attacked by pests or are generally more susceptible to disease.

Are mealybugs also dangerous for humans?

Mealybugs are annoying, but only attack plants. They are therefore neither dangerous for humans nor for animals.

Where do the mealybugs come from?

Usually you simply drag the pests into the house with a new plant. Even if the new acquisition looks healthy, it can still be infested with mealybugs. The animals hide very cleverly in the leaf axils or the bracts or the plant substrate is contaminated with lice eggs, from which new mealybugs hatch under favorable conditions - such as dry heating air.

The eggs can rest for months until the temperature and humidity are optimal. For this reason, many do not associate the plague with the newly purchased plant - after all, the time lag between the purchase and the outbreak can be up to a year. It is best to immediately repot new plants in fresh, disinfected substrate and then separate them first.

How fast do mealybugs multiply?

Mealybugs multiply very quickly: a single female can lay up to 600 eggs, from which the first larvae hatch after just a few days. These in turn develop so quickly that they start their harmful sucking activity within ten days. In addition, males are not absolutely necessary for reproduction, since mealybugs can also reproduce through virgin generation - that is, almost only female mealybugs can hatch from the 600 eggs of a single female, which in turn lay up to 600 eggs and so on ... No wonder so that at least eight generations of mealybugs are created every year!

What are mealybugs anyway?

Mealybugs are also known as mealybugs or root lice. They belong to the family of mealybugs (Latin: Pseudococcidae), which includes around 1000 different subspecies and is distributed worldwide. These are leaf sap sucking plant pests that prefer to be found on hard-leaved plants. In Germany, the long-tailed mealybug (lat. Pseudococcus longispinus) and the citrus smear louse (lat. Planococcus citri) are particularly common. As a rule, the animals are not very specialized, but rather attack different types of plants.

How can I strengthen my plants so that they are less likely to be infested with mealybugs?

Healthy plants in a healthy environment are less prone to infestation with mealybugs and other pests. Make sure the air humidity is pleasant, which is good not only for your respiratory tract, but also for your plants during the winter months. Avoid both over-fertilization and undersupply with nutrients - both weaken the plants and make them more vulnerable.

You can also improve the resistance of your plants with special means, for example by regularly spraying nettle or horsetail tea. Many plant lovers also swear by homeopathic tonics, which are usually administered with the irrigation water. In general, however, it helps if you plant and care for the plants according to their special needs.

Tips

If infested orchids are to be treated chemically, select a plant protection product that is explicitly orchid-friendly. Otherwise the exotic will not perish from the mealybug infestation, but from an unsuitable plant protection product.