Aphids: how to recognise them and rid your plants of them

Aphids are small insects, one to three millimetres long — green, black, grey, yellow or pink — that live in colonies and suck plant sap. They’re everywhere in spring, in the garden as well as on the balcony, and they find their way indoors too. Their strength: they multiply very quickly. Their weakness: they’re soft-bodied and easy to treat if spotted early.

Recognising them

Dense colonies on young shoots, flower buds and under leaves.
Curled or distorted leaves, shoots that shrivel.
A sticky deposit on leaves and the floor: honeydew, the sugar excreted by aphids. It attracts ants and encourages sooty mould, a black mould.
Ants climbing up and down the stem: they “farm” aphids for their honeydew. Their presence is often the first clue.

Roses, hibiscus, oleanders, citrus and broad beans — and, indoors, flowering plants and tender young shoots — are their favourite targets.

Getting rid of them, step by step

Remove most of the colony: a jet of water, or your fingers protected by cleaning gloves, on the worst-affected shoots. Cut off a heavily infested shoot.
Spray ready-to-use black soap for plants on the colonies, concentrating on the undersides of leaves and young shoots. Soap works on contact: it has to touch the insects.
Treat late in the day, never in full sun.
Repeat every five to seven days for three weeks: new generations hatch constantly.
Clean off the honeydew left on the leaves with a damp cloth to prevent sooty mould.

Preventing them

Don’t overdo nitrogen fertiliser: it produces tender, sap-filled shoots that aphids love. Choose a gentle fertiliser, such as our compost tea root feed, at the right dose.
Check young shoots every week in spring.
Clean the foliage once a month with black soap: it’s the simplest preventive measure.
In the garden, let your allies do their work: ladybirds, hoverflies and tits eat aphids by the hundred.

Frequently asked questions

Do aphids kill plants?
Rarely a mature plant, but they weaken it, distort its shoots and can transmit viruses. It’s best to act at the first colony.

What about washing-up liquid?
It contains fragrances, dyes and agents that can mark leaves. A black soap prepared for plants is safer. See black soap: uses and precautions.

What should I do about the ants?
Treat the aphids: without honeydew, the ants will leave of their own accord.

Need an opinion?

Send a photo of your plant to our Plant Doctor: the whole plant, a close-up of a leaf (top and underside) and the surface of the soil. The diagnosis is free. You can also drop by the studio at 6 Rue Zemmour, Aviation district, Rabat.

Whitefly: what to do about them on your plants?

You touch the plant and a little white cloud flies up, before settling straight back under the leaves: this is whitefly. These insects, one to two millimetres long with white powdery wings, suck sap from under the leaves. They love heat, which makes them common in Morocco, in vegetable gardens as well as indoors.

Recognising them

The adults: tiny white flies that take off when you move the plant.
The larvae: small flat scales, translucent or greenish, motionless under the leaves. They’re often mistaken for spots.
Honeydew: sticky leaves that later turn black with sooty mould.
Leaves that pale and yellow in patches.

Tomatoes, aubergines, citrus, hibiscus, lantanas, poinsettias and, indoors, plants with tender leaves are their favourite targets.

Getting rid of them

Isolate the plant if it’s in a pot: the adults fly from plant to plant.
Trap the adults with yellow sticky traps, which attract them. They also show whether the infestation is receding.
Spray ready-to-use black soap for plants, mainly under the leaves: that’s where the larvae live, and the soap reaches them on contact. Treat early in the morning or late in the day, when the adults are slower.
Repeat every five to seven days for three to four weeks: the protected eggs hatch in several waves.
Remove badly affected leaves covered in larvae.

Preventing them

Check the undersides of new plants’ leaves before bringing them in.
Ventilate: whitefly like warm, stuffy air.
Clean the foliage once a month with black soap, top and underside.
Don’t overfeed: a plant fed in moderation, such as with our compost tea root feed, produces less tender tissue.

Frequently asked questions

Why do they always come back?
Because only the larvae and adults that are hit die: the eggs survive. Regular spraying is everything.

Can I treat tomatoes on the balcony?
Yes, late in the day, rinsing the fruit before eating it.

See also: sooty mould, aphids and mealybugs and scale.

Need an opinion?

Sooty mould: the black deposit on leaves, and how to remove it

Are the leaves of your lemon tree, oleander or Ficus covered in a black film, like soot, that partly rubs off under your finger? That’s sooty mould. It isn’t a disease attacking the plant from within, but fungi growing on the surface of the leaves on a sugary deposit: honeydew.

Where it comes from

Honeydew is excreted by sap-sucking insects: aphids, mealybugs and scale, whitefly. It sticks to the leaves, and the sooty mould fungi feed on it. In other words: no sooty mould without insects. Treating it without looking for the insects means seeing it come back within three weeks.

Why deal with it

The black film blocks the light: the leaf photosynthesises less, the plant weakens, and a weak plant attracts more pests. On citrus, the fruit gets dirty too. Above all, the deposit is a sign that insects have moved in.

Cleaning it and treating the cause

Find the insects: turn the leaves over, look at the stems and leaf joints. Small shells or cottony clumps: mealybugs and scale. Colonies on the shoots: aphids. A white cloud flying up: whitefly.
Spray ready-to-use black soap for plants over all the foliage. It softens the deposit and acts on contact against the insects.
Wipe the leaves with cleaning gloves or a soft damp cloth, supporting each leaf with your other hand. Sooty mould comes off without hard rubbing.
Repeat every five to seven days for three to four weeks, long enough to deal with the insects.
Rinse small plants in the shower, protecting the soil.

Stopping them coming back

Clean the foliage once a month with black soap: honeydew doesn’t have time to build up.
Watch for ants climbing tree trunks: they often signal aphids or scale insects.
Keep plants vigorous: good light, the right watering, and gentle feeding with our compost tea root feed during the growing season.

Frequently asked questions

Is sooty mould contagious?
It follows the insects: they’re the ones that move from plant to plant.

Should I cut off blackened leaves?
No: once cleaned, they do their job again. Only remove those that are damaged.

Need an opinion?

Yellow leaves: why your plant is turning yellow, and what to do

Yellow leaves are the most common symptom in houseplants, and the most poorly treated. The reflex is to water more or add fertiliser; in most cases, that’s exactly the opposite of what’s needed. Yellowing is a signal: before acting, you need to read it.

One leaf, or several?

An old lower leaf that yellows slowly and then dries while the plant is making new leaves: that’s normal. The plant is recycling its old leaves. Remove it when it comes away on its own. However, if several leaves yellow at once, or if it’s the young leaves that are turning pale, there’s a problem to find.

The causes, from most to least common

1. Too much water

This is the number one cause. The roots sit in potting mix that no longer dries out, run short of air and start to rot; they can no longer supply the leaves, which turn yellow, often going soft. Push a finger several centimetres into the soil: if it’s damp, stop watering and empty the saucer or planter. If the soil stays soaked for several days and smells bad, you need to look at the roots.

2. Lack of light

A plant too far from the window can no longer feed all its leaves: it sacrifices the oldest, and its new shoots are small and pale. Move it closer to a window, out of the direct midday sun.

3. Lack of water

Rarer than people think. In this case, the leaves yellow and become dry and brittle, often with brown edges, and the soil is dry all the way down the pot.

4. A pot that’s too small or exhausted potting soil

Roots coming out of the holes, water running through the pot without being absorbed, a plant that has stopped growing in spring: it’s time to repot, in fresh potting mix such as our Signature Potting Mix. You can also come in for repotting at the studio.

5. Cold or a change of position

A draught, air conditioning too close, a house move: some plants, such as Ficus, react by yellowing and dropping leaves. Find them a stable spot.

6. Pests

Speckled yellowing, dull leaves, fine webbing or sticky deposits: look under the leaves. See our articles on mealybugs and scale, thrips and spider mites.

What not to do

Add fertiliser to a plant yellowing from overwatering: you’ll burn roots that are already damaged.
Change everything at once: moving, repotting, watering and feeding on the same day. Change one thing, and observe for two weeks.
Cut off all the yellow leaves at once on a weakened plant: leave it the ones that are still half green.

Need an opinion?

Send a photo of your plant to our Plant Doctor: the whole plant, a close-up of a leaf (top and underside) and the surface of the soil. The diagnosis is free, and you can also drop by the studio at 6 Rue Zemmour, Aviation district, Rabat, Tuesday to Saturday, 10am to 6pm.

Mealybugs and scale: how to recognise them and get rid of them

Mealybugs and scale insects are small sap-sucking insects that attach themselves to plants and draw out their sap. They’re common in Morocco, on houseplants as well as in gardens, and thrive in heat and dry air. They don’t kill a plant within days, but weaken it little by little. The good news: with regular treatment, you can get rid of them without chemicals.

Recognising them

Mealybugs

These are small white, cottony clumps, like flour or cotton wool, lodged in leaf joints, under leaves, along the veins and sometimes on the roots. They’re often found on Monsteras, Ficus, succulents and cacti.

Armoured scale

These are small brown, beige or grey shells, flat or domed, stuck to stems and under leaves. They’re often mistaken for part of the plant. Scratch with a fingernail: if the shell comes off, it’s a scale insect.

The tell-tale signs

Sticky leaves and floor: this is honeydew, the sugar excreted by the insects.
A black dust on the leaves: sooty mould, a fungus that grows on the honeydew.
Yellowing leaves and a plant that has stopped growing.

Getting rid of them, step by step

Isolate the plant: these insects easily spread from one plant to another.
Remove them by hand: a cotton bud dipped in soapy water or 70% alcohol for mealybugs; a fingernail or an old toothbrush for armoured scale. Cut back heavily infested parts.
Clean the foliage, top and underside, with cleaning gloves or a damp cloth, and rinse the plant in the shower if its size allows.
Spray ready-to-use black soap over the whole plant, concentrating on the undersides of leaves and the leaf joints. Soap works on contact: it has to touch the insects.
Repeat every five to seven days for at least a month: the protected eggs hatch in several waves.

Preventing them

Inspect every new plant before putting it with the others.
Dust the leaves regularly: you’ll spot the first insects early.
Avoid too much nitrogen fertiliser, which produces the tender shoots they love.

Frequently asked questions

Are mealybugs and scale dangerous to people or pets?
No, they only attack plants.

Should I throw the plant away?
Rarely. Only a heavily infested plant that’s already weakened is sometimes no longer worth the fight. If in doubt, ask us.

Need an opinion?

Thrips: recognising the silvery marks and taking action

Thrips are minute, elongated insects one to two millimetres long, very common in Moroccan crops and happy to move into our homes. They rasp the surface of leaves to suck out the contents. Discreet and quick, they hide under leaves and in young shoots; you often notice the damage before you see them.

Recognising them

Silvery or bleached patches on the leaves, as if the surface had been scratched.
Tiny shiny black dots in the middle of these patches: these are their droppings.
Young leaves that are distorted or marked as soon as they emerge.
The insects themselves: shake a leaf over a sheet of white paper and you’ll see tiny pale or dark slivers moving.

Monsteras, Philodendrons, Anthuriums, Ficus and flowering plants are among their favourite targets.

Getting rid of them

Isolate the plant: thrips fly and jump from one plant to another.
Shower the foliage, top and especially underneath, to knock off as many insects as possible. Cover the soil so they don’t fall into it.
Spray ready-to-use black soap over the whole plant, concentrating on the undersides of leaves and the heart of young shoots.
Repeat every four to five days for three to four weeks: their larvae hide, and part of their life cycle takes place in the soil.
Scrape off and replace the top layer of soil to a depth of one or two centimetres, where the pupae hide.

Blue or yellow sticky traps pushed into the pot let you track the infestation and know when it’s over.

Preventing them

Thrips like hot, dry air: misting around plants with a fine-mist spray bottle disrupts them.
Inspect new plants and bunches of cut flowers, which often bring them into the house.
Clean the foliage regularly: you’ll spot the first silvery marks early.

Need an opinion?

Spider mites: spot them early and save your plants

The spider mite isn’t a spider but a tiny mite, barely visible to the naked eye, often reddish-orange, sometimes yellow or greenish. It pierces leaf cells to suck out their contents. It loves hot, dry air: summer in Rabat, the chergui wind and air conditioning give it ideal conditions.

Spotting them

Dull leaves speckled with countless tiny yellow or white dots, which eventually turn yellow or brown.
Very fine webbing, like silk, under the leaves and in the leaf joints, when the infestation is advanced.
A simple test: wipe a white tissue under a leaf. Red or brown streaks: that’s them.

Alocasias, Calatheas, Marantas, Ficus and indoor palms are among their favourite targets.

Getting rid of them

Isolate the plant.
Shower the foliage thoroughly, especially the undersides of the leaves: water knocks off a large share of the mites and destroys their webs.
Wipe each leaf, top and underside, with cleaning gloves or a damp cloth.
Spray ready-to-use black soap, concentrating on the undersides of the leaves.
Repeat every four to five days for three weeks: a new generation hatches in under a week when it’s hot.

Stopping them coming back

Raise the humidity around sensitive plants: mist with a fine-mist spray bottle, group plants together, or stand pots on a tray of damp pebbles.
Keep them away from air-conditioning vents and radiators.
Check the undersides of the leaves every week in summer: they’re far easier to treat early on.

Need an opinion?

Gnats in your plants: how to get rid of them

Little black flies buzzing around your pots and taking off when you water: these are sciarids, known as fungus gnats. The adults are mostly a nuisance; it’s their larvae — tiny white worms with black heads — that live in damp soil and feed on organic matter and sometimes young roots. The good news: they almost always point to overwatering, which is easy to correct.

Why they appear

Soil that stays permanently damp on the surface.
A potting soil very rich in organic matter, or a bag of potting soil that’s already contaminated.
A planter or saucer where water sits.

Getting rid of them

Let the surface dry to a depth of two to three centimetres between waterings: the larvae can’t survive in dry soil. This is the most effective measure.
Water through the saucer: the soil drinks from below and the surface stays dry. Our planters with reservoir saucers are made for this.
Cover the surface with a one- or two-centimetre mineral layer, such as pozzolana: the adults can no longer lay eggs in it.
Trap the adults with yellow sticky traps pushed into the pots.
If the infestation is heavy, repot in fresh, airy potting mix, such as our Signature Potting Mix, after removing the old soil.

Frequently asked questions

Are fungus gnats harmful to the plant?
For a healthy adult plant, rarely. For seedlings, cuttings and plants already weakened by overwatering, the larvae can damage the roots.

Are they fruit flies?
No: fruit flies, which are paler, hover around the kitchen and ripe fruit. Fungus gnats, black and slender, stay close to the pots.