Control and prevent aphids, mealy bugs, thrips and other pests on your houseplants

Aphids are a real pest on houseplants. They measure between 1 and 7 mm, are usually black, white or green (exceptionally also yellow, red or purple) and have a soft, pear-shaped body, with two protuberances at the abdomen. 

They poke a hole in the leaves of your plants and then feast on the plant sap. This obviously damages the leaves and unbalances the plant. The plant weakens and because of the damage, deformations are possible which makes the plant visually a lot less attractive. Aphids reproduce very quickly. In no time, an aphid infestation can have your plant in its grip. Fortunately, controlling an infestation of aphids is relatively easy. 

Aphids secrete honeydew. This is a sticky substance that can also attract ants. And you definitely prefer to keep them out of your home. In addition, this honeydew can cause sooty mould. This creates black spots on the leaves. Aphids are usually found on plants with soft leaves (which are easier to sink their teeth into) such as the calathea, alocasia or peace lilies.

Fungus gnats

Fungus gnats are not a pest on your houseplants themselves, but they are in their potting soil. Technically, fungus gnats are not flies but mosquitoes.

You notice the presence of fungus gnats best when watering. If there is a plague of fungus gnats, they will fly up en masse when watering. They are 3 to 5 mm in size and like a moist, warm environment in potting soil. The flies are very annoying, but do little damage.

The larvae of fungus gnats is a different story. These are 5 to 12 mm, white-transparent in colour with a black head. Young larvae eat rotting material, algae and fungi in the potting soil. Larger larvae eat root hairs, soft roots or even entire young plant stems. This damage makes it easier for fungi to gain a foothold on the plant. Seedlings, cuttings and young plants are especially susceptible to sciarid flies, especially if they are in heated conditions. Potted azalea or begonia, among others, are also quickly affected by fungus gnats.

A mealybug is a small insect about 3 to 6 mm in size that appears to be coated in a white powdery layer. Females produce a white, woolly secretion. The mealybug is most common on houseplants such as bromeliads or orchids, but also on cacti. 

Mealybugs are not harmful to humans, but your plants suffer quite a bit. These white rascals feed on various plant parts, causing loss of nutrients. The mealybug also leaves behind a secretion and honeydew which attracts fungi. This too will weaken the plant. Moreover, ants also love honeydew. Mealybugs like a humid environment with lots of draughts.

Controlling mealybugs 

Mealybugs on your houseplant can be controlled with simple remedies. Fill a plant sprayer with water and add a dash of washing-up liquid. Shake well and then spray the entire plant with this soapy water. Repeat after a week if necessary. Of course, you can also immediately use an organic insect spray or use their natural enemies. The lacewing is a natural enemy of the mealybug, among others. Their larvae literally eat the mealy bug. 

Scale insect

Scale insects are barely 1 to 3 mm in size, but you can still see them with the naked eye. This is because they often live in large groups. You can recognise a scale insect by its horny shell. Scale insects suck on the leaves of your plant after which it injects a toxic substance into your houseplant. Plants with a woody stem are particularly susceptible and it also likes to stay on somewhat older plants. The scale insect can also be found on orchids and all kinds of palm species. Scale insects also find very calcareous soil extremely fine.

Controlling scale insects 

Controlling scale insects on your houseplants is very similar to controlling mealybugs. Using a plant sprayer filled with water and a dash of washing-up liquid will go a long way. Be careful not to make the potting soil too wet. The water spray should also be hard enough to remove all the scale insects that cling to the leaves. Another remedy is dabbing with alcohol. Soak a cotton swab in alcohol and dot the scale insects one by one. Within a minute, you will find it easier to remove them manually. An organic insect spray is always a possible solution to combat the presence of scale insects on your houseplant.

Spider mites and aphids are very similar in appearance, but spider mites are definitely not aphids. They are actually mites that are often found on the underside of your houseplant's leaves. They feed on leaf juices by poking holes in the leaf. This causes leaves to develop yellow-brown spots. Very fine cobwebs can also be a sign that your plant is suffering from spider mites. The 'cobweb' seems to be thrown haphazardly on the plant, instead of following a nice structure like that of a spider.

Spider mite control

Spider mites are best controlled using water. Fill a plant sprayer with water and literally chase the mites away with a jet of water. It is best to cut away the worst affected parts of your plant to give the healthy parts every chance. You can also let their natural enemies do the work. Predatory mites actively hunt spider mites, stopping the infestation.

Spider mite prevention 

Proper misting with the plant sprayer not only chases away spider mites if there are any, but also works preventively. Mites like it dry and warm. You should also repot your plants often enough, or at least add a layer of fresh potting soil. Mites thrive in old, exhausted potting soil.

Thrips

Thrips look a lot like fungus gnats, but are different. They cannot necessarily fly well, but do use their little wings to jump from one plant to another. The larvae of thrips live on the leaves of your houseplants and feed on sap from the leaves. The result is golden or silvery spots. Thrips have a long, thin body and do not grow larger than 2 mm. They can be brown or black. Larvae of thrips are yellow-white in colour and do not yet have wings. In the first stage, they are barely half a millimetre in size. Small buggers, then, that can have big consequences.

Fighting thrips

The first step to take if you discover thrips on one of your houseplants is to isolate that plant immediately! Then start working with sprays or natural enemies. Breeding bags or scatter boxes containing predatory mites or predatory bugs are an excellent solution in that respect.

Preventing thrips 

Thrips like areas with low humidity. To prevent thrips from attacking your plant, spray them regularly with a plant sprayer. Nutrients, too, are extremely important. A weakened plant is less able to defend itself against pests, so a pest also spreads more quickly.