Why do plant lice appear and how to get rid of plant lice with natural preparations?

You, just like any true gardening enthusiast, are surely deeply saddened when you see that pesky aphids have infested your plants. This is a common occurrence on almost all plants, and it is rare for any plant to remain untouched by these little predators.

Below, we explain why plant lice appear, how to get rid of them with natural remedies from your home and, most importantly, how to prevent them from reappearing.

What are plant lice and how do they develop?

To know how to get rid of them or prevent them from appearing, you must first know what plant lice are and how they develop.

Plant lice (Aphididae, arthropods from the eukaryotic domain) They are small insects that feed on plant sap, most often from young leaves, buds and stems. They are attracted to plants that are in a phase of intensive growth, as they contain more nutrients then, especially nitrogen, which favours their reproduction.

They develop at an incredible speed. Under favourable conditions, when humidity and the environment are favourable, a single female can produce dozens of new individuals without mating in a very short time. This is why an infestation often spreads at lightning speed.

As well as sucking the juices from plants like leeches, aphids also secrete a sticky substance known as honeydew, which promotes the growth of fungi and further weakens the plant.

Why do plant lice appear on plants?

Plant lice appear when conditions are favourable, and the ideal conditions would be:

• Warm and dry weather, especially in spring and early summer
• Excessive fertilisation with nitrogenous fertilisers, which makes plants „juicier“ and more attractive to insects
• Poor air circulation between plants
• Lack of natural enemies, such as ladybirds and other insects that eat them

Which types of plants do aphids attack?

There are many genera and species, but the most common are green, black and white plant lice.

The green ones are the most widespread and they love roses, vegetables and fruit. They blend in easily with the leaves and multiply very quickly in spring, especially if the days are rainy. You will find them on the newly emerged rosebuds, on the leaves of fruit and vegetables.

White plant lice favour houseplants and look like ash or cotton wool. They should be distinguished from sooty mould, which is a fungal disease of the plant. Whiteflies also favour citrus and ornamental plants.

Black aphids attack beans, roses and fruit trees. They are dark in colour and easy to spot, and can cause the rapid wilting of young shoots.

How can you tell if plant lice have infested a plant?

Some of the most common signs are:

• Curled, deformed or yellowed leaves
• Sticky surface on the leaves and around the plant
• The presence of small green, black, yellow or whitish insects on the underside of leaves
• Slowed plant growth, visible stunting

The sooner a problem is noticed, the easier it is to solve using natural methods. You should first try natural remedies, but if you don't see any results, be sure to seek a solution from an agricultural chemist.

Natural remedies for removing mealybugs

The good news is that plant lice can be successfully controlled without the use of harsh chemicals. Here are a few tried and tested natural solutions:

1. Soap and water solution

One of the most commonly used and safest methods.

How to make:

• 1 tablespoon of liquid natural soap (without detergents and perfume)
• 1 litre of lukewarm water
• a few drops of oil to make the plant lice stick

Spray the plants with a spray bottle, especially the undersides of the leaves. The soap breaks down the aphids' protective waxy coating, causing them to die.

Repeat the procedure every 2–3 days until they are removed.

2. Garlic tea

Garlic has natural antibacterial and insecticidal properties. Try the following recipe for a few days:

• Finely chop 2–3 cloves of garlic.
• Pour over with 1 litre of boiling water
• Leave to stand for a few hours, then strain.

Spray the solution on the plants once a day for a few days. Be persistent, as this natural antibiotic takes a little time to work.

3. Nettle solution

Nettles strengthen plants and repel pests. For this natural insecticide, you will need a handful of fresh nettles and 1 litre of water.

Leave stinging nettle in water for 24 hours, strain it and spray the plants evenly with a sprayer. As well as repelling aphids, it also acts as a mild natural fertiliser on substrate.

4. Alcoholic solution for topical treatment

For a minor infestation, you can use cotton wool soaked in diluted alcohol (1 part alcohol, 3 parts water) and gently wipe the areas where your pets are present.

For the same purpose, people also use diluted vinegar, but you need to be careful as it can burn the plant's leaves. Therefore, always dilute it well and be sure to test it on one leaf first. Only then, once you're sure everything is alright, should you spray the entire plant.

5. Bicarbonate of soda against mealybugs

Bicarbonate of soda can help indirectly, and people often mix it as the number one remedy in the fight against these insects. However, it is not; it is much better known as a natural remedy against fungi such as powdery mildew. A bicarbonate of soda solution can help if you mix it with soapy water, but on its own it is unlikely to have much effect, especially if the colonies have already developed significantly.

6. Essential oils against mealybugs

Some of us have tried the power of essential oils to combat aphids with great success. Essential oils, particularly peppermint, lavender and tea tree oil, have proven to be an effective natural aid in the fight against aphids, thanks to their powerful aromatic and biologically active ingredients. These oils work by repelling insects with their strong scent and disrupting their feeding, and in some cases, they can also kill them on direct contact.

However, due to their concentration, they must always be used diluted to avoid damaging the leaves. Typically, 2–5 drops of essential oil are added per litre of water, along with a few drops of natural liquid soap which helps the solution adhere better to the plant. Spraying should be done from as great a distance as possible, in a fine mist, so that the leaves are lightly dampened rather than soaked. It is recommended to treat the plant once or twice a week, after first testing on a single leaf. This method prevents scorching, while the scent of the essential oils effectively repels aphids and reduces their re-appearance.

Is ash good against mealybugs?

Ash from wood, and even from cigarettes, is traditionally used against mealybugs and to prevent the development of fungal diseases, but with varying effectiveness and safety.

Wood ash contains mineral salts and has a slightly alkaline effect which:

• Impedes the movement of plant lice
• can partially dry them out
• simultaneously slightly enriches the soil with potassium

How to use:

• It is best to sprinkle a thin layer over substrate around the plant
• or very lightly dust the lower parts of the stem (not directly on the leaves in large quantities)

You shouldn't overdo it, as too much ash alters the soil's pH and can harm plants. The effect of wood ash is mainly preventative, even with minor infestations.

On the other hand, cigarette ash can contain harmful chemicals from tobacco, which can damage plants and soil, so it is not recommended due to its toxicity.

What should you do when natural remedies cannot help with mealybugs?

If after a few days you see no change and the aphids are still active and becoming more numerous, seek out milder biological preparations available from agricultural supply shops, which are safe for plants and beneficial insects when used correctly.

Try natural ingredients, but use them as a preventative measure too. As soon as spring arrives, help your plants defend themselves against these pests that harm their growth and proper development.