Scale Insects Control: The Best Tips & Home Remedies

Scale insects damage our plants and are also spreading further and further. What to do in case of an infestation and how to fight scale insects, you can find out here!

Scale insects: Interesting facts & lifestyle

• Scale insects (Coccoidea) belong to the aphids. There are over 4000 species worldwide.
• Scale insects grow between 0.6 mm and 6 mm in size.
• Female scale insects form a protective armour in the colour of the host plant, under which they lay their eggs (up to 2000 annually!). They become a danger because of the mouthparts they use to suck the plant dry. The scale insects also release a secretion into the plant’s circulation, further weakening the plant. Male scale insects, on the other hand, are harmless because they have no mouthparts.
• Scale insects infest not only indoor plants, but also useful plants in the garden.
• The pests spread mainly in winter and spring.

Scale insect infestation: Indications

• Leaf shedding or discoloured leaves
• Unopened buds or crippled flowers
• Shoots and branches that appear encrusted
• White webs: Wool lice spread. They belong to the scale insect family.
• Leaves, stems and petioles with brown or green humps (scale insect carapaces)
• Sticky coating (also known as honeydew): Scale insects feed on plant juices and later on the sugary components, leaving sticky splashes on the leaves or next to the plant.
• Sooty mold infestation & ants: The sticky juices attract ants and also provide the basis for sooty mildew fungi, which appear as black discolouration on the leaves.

Scale insects: Occurrence

Indoor plants, which are particularly frequently affected:

• Palm tree
• Ficus
• Flamingo flower
• Succulents
• Orchid
• Citrus plants
• Laurel
• Rubber tree
• Strelitzie
• Cacti
• Ivy

Crop plants that are particularly frequently affected:

• Cherry tree
• Apple tree
• Berry bushes
• Pear tree
• Peach tree
• Plum tree

Scale insect infestation: Causes

Even in plants, weakened defences are ultimately responsible if they cannot defend themselves against the pests. Healthy plants, on the other hand, are resistant and can fend off individual pests. Weakened defences are caused, for example, by

• Wrong location
• Low humidity
• Lack of water or nutrients
• Overfertilization
• Incorrect water supply

Already when buying plants, look out for possible pest infestation. If you put a new plant with scale insects in your room, the pests can spread quickly!

Scale insect control: Measures

Scale insects are not only extremely harmful to your plants, they also multiply vehemently and therefore spread to surrounding plants. You should therefore place the infested plant in a separate room where it is best to keep it cool and bright. If only certain parts of the plant are affected, it may help to cut off and throw away these parts of the plant. A plant shower (upside down) with soap can also help. However, a strong jet is necessary and it could happen that the eggs are further spread on the plant. Therefore the shower is only a method for very young animals that have not yet settled down.

Attention: If you place plants in a winter home over the winter, make sure that no scale insects are present – otherwise they will spread to all surrounding areas.

Targeted pest control

• Use tweezers or a sharp knife to remove scale insects from the plants one by one and crush them in a kitchen roll! The pests do not run away, so this is an efficient, albeit laborious, method. Make sure that you carry out the procedure in a room with sufficient light so that you don’t miss any scale insects. Warning: you must not scrape off the scale insects, otherwise the larvae could spread on the plant. In addition, you should always clean the tool on a kitchen towel or soak it in alcohol so that the young animals do not spread further.
• Dip a cotton swab in spirit and press it onto the scale insect’s shell. This method first destroys the carapace and then lets the pest die.
• Tea Tree Oil: Apply the pungent Tea Tree Oil to the pest’s carapace with a cotton swab – but be careful not to drip it on the leaves as it can damage the plant.

Fighting scale insects: With home remedies

Before you use chemical means to fight scale insects, you should first try household remedies. Here you can make different recipes, which are applied repeatedly to the plant with a spray bottle or brush until the pest has disappeared.

• Stinging nettle brew: Put 0.5 kg of stinging nettles together with 5 l of water in a container and leave the mixture to stand for three days with the lid closed. In the meantime, stir occasionally! Finally, the brew has to be filtered. This household remedy is only recommended for plants in the garden, as a penetrating smell is produced.
• Nicotine brew: Fill 1 l of hot water into 200 g of tobacco and leave the liquid to stand for at least one hour with the lid closed. The treatment should be repeated every three days.
• Curd soap-spirit mixture: Mix 15 ml of liquid curd soap with 15 ml of methylated spirits and 1 l of water and leave to stand for 30 minutes. Caution: Test the mixture on a leaf beforehand, as some plants do not tolerate the solution.
• Rain fern brew: Chop 150 g fresh rain fern leaves small and fill them into a container. Fill up with 5 l of hot water and let the brew steep for about 10 minutes. Strain the brew and spray the liquid generously. Repeat the application at least three times within a week.

Fighting scale insects: With beneficial insects

If you have a pest infestation in your garden, you can release beneficial insects to control the scale insects. They are positioned on the affected plant and destroy the pests.

The following beneficial organisms are suitable for this purpose:

• Ichneumon flies
• Ladybird
• Hoverflies
• Gall midges
• Earwigs
• Lacewings

Caution: Since ants often spread in affected plants, they must also be controlled, otherwise they will attack the beneficial insects.