I see insects on my plant: causes and solutions

First step: isolate immediately

As soon as you spot insects on a plant, move it away from others first and foremost. Most pests spread through direct contact — touching leaves, water splashes, clothing. An isolated plant can no longer contaminate the rest of your collection.

Place it in a separate room if possible, or at least a meter away from other plants. Then inspect neighboring plants: they may already be affected without you having noticed.

"Isolate first, identify next, treat last.
In that order, not the other way around."

1. Fungus gnats — sciarids

Small black gnats flying around the pot

Fungus gnats are small black gnats about 2mm long that flutter around the soil and plant. They are attracted to moist substrates where they lay their eggs. It is the larvae — invisible to the naked eye — that cause damage by feeding on fine roots.

Good news: adults do not attack plants. It is the larvae that weaken the roots. A mild infestation is rarely fatal, but a severe infestation can seriously weaken the plant.

Small black gnats flying Mainly present around moist soil Microscopic white larvae in the substrate Plant wilting for no apparent reason

✔ Solution Let the soil dry completely between waterings — larvae do not survive in dry substrate. Place yellow sticky traps on the surface of the pot to catch adults. Water with water mixed with neem oil (a few drops per liter). If the infestation is severe, replace the top 3-4 cm of the substrate. Repeat treatment for 3 to 4 weeks.

2. Mealybugs

White cottony substance on stems and leaves

Mealybugs are immediately recognizable by their appearance: a white, cottony or woolly substance that looks like mold or cotton. They cluster in leaf axils, along stems, and under foliage. They suck sap and excrete sticky honeydew that promotes the development of black sooty mold.

White cottony substance on stems and leaves Sticky honeydew on leaves Black sooty mold on the honeydew Yellowing and falling leaves

✔ Solution Manually remove mealybugs with a cotton swab soaked in 70% alcohol. Then treat the entire plant with diluted neem oil (5 ml per 1L of water + a few drops of liquid soap), focusing on the undersides of leaves and axils. Repeat every 5 days for 3 uninterrupted weeks — eggs hatch continuously and regular treatment is necessary for effectiveness.

3. Spider mites

Tiny dots + fine webs under leaves

Spider mites are microscopic mites — barely visible to the naked eye. They are mainly recognized by their damage: yellow or beige spots evenly distributed on the leaf blade, and fine silken webs under the leaves and between the stems. They proliferate in hot, dry air, especially in winter with heating.

Even yellow/beige spots on leaves Fine white webs under leaves Leaves dulling and losing their luster Worsened by hot and dry air

✔ Solution Spray the undersides of the leaves generously with cold water — spiders hate humidity. Then treat with diluted neem oil or an insecticidal soap. Increase the ambient humidity around the plant (humidifier or grouping plants). Repeat every 5 days for 3 to 4 weeks. Spider mites develop resistance quickly — alternate treatments if necessary.

4. Aphids

Small green, black or white insects on new shoots

Aphids are among the easiest pests to identify: they are visible to the naked eye, grouped in colonies on new shoots, buds, and the undersides of leaves. They suck sap from the tender parts of the plant and excrete sticky honeydew. They reproduce very quickly — a colony can double in a few days.

Small visible green, black or white insects Clustered on new shoots and buds Sticky honeydew on leaves Ants present — they protect aphids

✔ Solution Rinse the plant under a stream of water to physically dislodge the colonies. Then treat with a diluted black soap solution (1 tbsp per 1L of water) or neem oil. Focus on new shoots and the undersides of leaves. Repeat every 3 days for 2 weeks. Aphids are among the easiest pests to eliminate if caught early.

5. Whiteflies

Cloud of small white flies with slightest movement

Whiteflies are small, winged white insects that fly up in a cloud when the plant is shaken. Their larvae remain fixed under the leaves and suck sap. Less common than other indoor pests, they can nevertheless spread quickly and are sometimes resistant to conventional treatments.

White cloud with every plant movement Translucent yellow larvae under leaves Honeydew and black sooty mold Yellowing and curling leaves

✔ Solution Place yellow sticky traps around the plant to catch adults. Treat the undersides of leaves with neem oil or an insecticidal soap. Repeat every 5 days for 4 weeks — the life cycle of whiteflies is longer than that of other pests. Ventilate the room regularly.

⚠ Golden rule of treatments

Never treat just once and wait. All pests have a reproductive cycle — eggs hatch after the first treatment. You must repeat treatment every 5 to 7 days for at least 3 weeks to break this cycle. A single treatment is never enough.

Preventing infestations

The best strategy against pests remains prevention. Regularly inspect the undersides of your leaves — once a week is enough. Infestations detected early can be treated in a few days; detected late, they can take months.

Maintain good ambient humidity: most pests (spider mites in particular) proliferate in dry air. Avoid grouping newly purchased plants with your existing collection without a 2-week quarantine period. And consider a preventative neem oil treatment once a month in spring and summer.

Summary table — identify your pest

What you see	Probable pest	Key treatment	Duration
Black gnats flying near soil	Fungus gnats	Dry soil + yellow traps + neem	3–4 weeks
White cottony substance on stems	Mealybugs	70% alcohol + neem oil	3 weeks
Yellow spots + fine webs under leaves	Spider mites	Cold water + neem + humidity	3–4 weeks
Green/black insects on new shoots	Aphids	Water spray + black soap	2 weeks
White cloud with every movement	Whiteflies	Yellow traps + neem	4 weeks