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Article: Keep harmful insects away from your growing space

Keep harmful insects away from your growing space

🌿 Naturally fight against pests in indoor and outdoor cultivation 🌱

Infestation of black aphids on the stems and young leaves of a green plant, common pests in indoor and outdoor cultivation.

Introduction

Crops, whether indoors (🏡 greenhouses, conservatories, grow-rooms) or outdoors (🌻 vegetable gardens, gardens), often face harmful insects called pests. 🐜 Aphids, 🕷️ mites (red spiders), thrips, 🪰 whiteflies, and 🐛 caterpillars are among the most commonly encountered pests in cultivation.

Rather than resorting to chemical pesticides, it is possible to protect your plants in a natural and ecological way. This article offers preventive methods to avoid infestations, as well as effective natural treatments against various pests, suitable for both indoor and outdoor use. Each solution is accompanied by usage tips, targeted pests, and precautions to take in order to be both clear and educational.

✅ Prevent pests naturally

Prevention is the first step in an effective fight against pests. By adopting good cultural practices, we make the environment less favorable to pests, which significantly limits the risk of infestation. Here are some natural preventive techniques, applicable both indoors and outdoors:

✨ Soil mulching

An organic mulch at the base of plants protects the soil and limits pests. Mulching involves covering the soil with organic materials (straw, bark, grass clippings, dead leaves...) or mineral materials. This protective layer provides multiple benefits: it maintains good soil moisture, prevents water stress that can weaken plants, and regulates soil temperature (useful outdoors during heat or cold spikes). Indirectly, a mulched soil is more fertile and balanced, making plants more vigorous and less susceptible to attacks. Additionally, mulching limits the growth of weeds that could serve as refuge or food for certain pests. Finally, a thick mulch can act as a physical barrier for soil insects.

⚠️ Precaution: Avoid overly thick or waterlogged mulching that could encourage slugs and snails (other pests in the vegetable garden). Indoors, you can mulch large containers or planters (with clay balls, coconut coco...) to maintain humidity, while ensuring that no pests are hiding there.

🔄 Crop rotation

Outdoors (vegetable garden, open ground), practice crop rotation from year to year. This involves not replanting plants from the same botanical family in the same spot immediately. By changing the location of vegetables and flowers each season, you disrupt the cycle of pests specific to a given plant. For example, if a plot has been infested with cabbage white caterpillars, avoid replanting cabbages there the following year: any residual eggs or larvae will not find their host plant and will not be able to proliferate. Similarly, rotation helps prevent soil diseases. In indoor cultivation (soilless, containers), one can draw inspiration from this principle: do not always grow the same variety in the same potting soil, or replace/substitute the substrate between two crops to eliminate any potential pest eggs.

⚠️ Precaution: Maintain a rotation of 3 to 4 years for sensitive vegetables (tomatoes, cabbages, leeks, carrots…) to completely break the cycle of specialized pests.

🌸 Companion plants and biodiversity

Certain companion plants can repel pests or divert them from your main crops. This is an effective plant companion technique, especially outdoors or in a greenhouse. Here are some practical examples:

  • 🌼 Marigolds (Tagetes)
    Marigolds emit a strong odor that repels several insects and soil parasites. They are known to reduce harmful nematodes and deter certain insects while attracting pollinators. They are often planted in the middle of the vegetable garden, between the vegetables.

  • 🌺 Capucine
    The nasturtium is used as a trap plant for aphids: it strongly attracts them, which will colonize its stems and leaves rather than your important crops (roses, vegetables). You just need to remove or destroy the infested nasturtium.

  • 🧄 Garlic, onion, chives (Alliaceae)
    These sulfur-containing plants have a general repellent effect. When planted at the foot of roses, tomatoes, or salads, they can inconvenience aphids, flies, and fungal diseases.
    (Your article already contains two garlic-based tips: garlic infusion and olfactory barrier, so we will not go into detail about them again.)

  • 🌱 Basil, mint, rosemary, and aromatic herbs
    These herbs release fragrant essential oils that disrupt harmful insects. For example, basil planted near tomatoes helps to repel whiteflies and thrips, while peppermint deters aphids and ants.


🐝 Attract beneficial insects

In addition to repellent plants, one can also sow attractive plants (trap plants) to divert the attention of pests or attract their natural predators.

👉 Flowers rich in nectar and pollen such as phacelia, borage, cosmos, chamomile, or sunflower attract ladybugs, hoverflies, parasitic wasps, and other beneficial auxiliary insects. These predatory insects will then help to limit pests.

👉 Indoors or in a greenhouse, place pots of aromatic plants or flowering plants near crops or at the entrance to enjoy the same benefits.


🌡️ Climate control and hygiene

Environmental conditions play a crucial role in the proliferation of pests, particularly indoors where the ecosystem is restricted. Here are some important preventive measures:

💧 Humidity

  • Maintain appropriate humidity.
  • Example: red spiders (spider mites) love dry air. Regularly spraying water around the plants (particularly under the leaves) increases humidity and slows their spread.
  • However, be aware: excessive stagnant humidity can promote soil flies (sciarids) and certain fungal diseases. Therefore, find a good balance and aerate if necessary.

🌬️ Temperature and ventilation

  • Aerate the greenhouses and enclosed spaces to avoid excessive heat and stagnant air, conditions that favor whiteflies and fungal diseases.
  • Good air circulation limits fungal spores and hinders fragile flying insects.
  • In indoor culture, the use of oscillating fans helps to strengthen the stems while discouraging flying insects from settling permanently.

🧹 Hygiene and maintenance

  • Regularly disinfect your growing equipment (stakes, pruning tools, reused pots) to avoid transmitting eggs or pathogenic germs from one plant to another.
  • Indoors, put the new plants or cuttings in quarantine for a few days to detect and treat any potential pests before introducing them into the main space.
  • Frequently remove dead or diseased leaves, as they often harbor insects and mold.
  • Avoid leaving plant debris on the ground, in the garden or the greenhouse.

🔍 Regular surveillance

Inspect frequently:

  • The top and bottom of the leaves 🍃
  • The new shoots 🌱
  • The floral buds 🌸

🔍 Regular surveillance

Inspect frequently:

  • The top and bottom of the leaves 🍃
  • The new shoots 🌱
  • The floral buds 🌸

Early detection of the first pests (aphids, scale insects, butterfly eggs, spider mite webs) allows for quick action before a population explosion.

  • Use yellow or blue sticky traps 🟡🔵 to early detect whiteflies, thrips, etc.
  • Manually eliminate at the first signs: crush a few aphids, remove a caterpillar, or shower a plant infested with thrips, in order to prevent their reproduction.

⚠️ This vigilance is even more crucial indoors, where pests have no spontaneous natural predators!

🌿 II. Natural treatments against pests

Spraying a natural insecticide on green plants to eliminate pests, treatment against insects in indoor cultivation.

"Despite all precautions, infestations can still occur. Fortunately, there are many biological treatments available to combat targeted pests, without polluting or compromising the health of your crops."

We present below proven natural remedies – plant extracts (manures, infusions), homemade solutions (black soap, oils) or the use of beneficial insects – along with their respective effectiveness, targeted pests, and usage precautions.


Nettle and horsetail purines

Plant extracts are fermented extracts of macerated plants, widely used in organic gardening. Two major classics are nettle manure and horsetail manure, with complementary properties:


Nettle Purin (Urtica dioica)

It is a versatile preparation, both fertilizing and insect-repelling. Used in diluted foliar spraying, nettle manure is an effective natural repellent against aphids and mites. It also strengthens the plants' defenses due to its richness in minerals, making them less susceptible to diseases.

💡 Preventive use:

  • In spring, spray a dilution (~10% of manure) on the foliage to deter aphids from attacking.

💪 Curative use:

  • Spray the diluted nettle manure directly on a plant infested with aphids or spider mites.
  • "Its smell and its compounds disturb pests and can make them drop off or flee."

🐛 Targeted Ravagers:

  • Aphids (all species)
  • Mites and red spiders
  • Aleyrodidae (moderate effectiveness)
  • Soft-bodied insects

⚠️ Precautions:

  • Never apply pure manure (undiluted) on the leaves: it is very concentrated and can burn the plant.
  • Avoid treatments during full bloom (the highly nitrogenous nettle manure could disrupt it).
  • Do not apply in direct sunlight (risk of phytotoxicity).
  • Indoors, apply sparingly (strong fermentation smell) and ventilate after treatment.

🌾 Horsetail pudding (Equisetum arvense)

Horsetail is rich in silica and alkaloids. Its manure is mainly known as a preventive fungicide (against downy mildew, powdery mildew, rust...), but it also has an interesting insect-repellent action.

🦠 Usage:

  • Alkaloid substances help to repel or combat certain insects such as the leek moth (miner), as well as mites and red spiders.
  • Use as a diluted foliar spray (~10–20%) on sensitive crops:
    • Potatoes 🥔
    • Tomatoes 🍅
    • Rose bushes 🌹
    • Leeks
    • Fragile fruit trees 🍏
  • Renew approximately every 2 weeks during high-risk periods.

🐛 Targeted Ravagers:

  • Mites (spider mites)
  • Specific insects of the vegetable garden (leek moth, possibly cabbage flea beetles)
  • Cryptogamic diseases (downy mildew, rust, powdery mildew...)

⚠️ Precautions:

  • Respect the recommended dilutions (~1 part of manure to 5 parts of water according to the recipes).
  • Shake the mixture before use, as it may settle.
  • Apply preferably in the evening or on overcast days to maximize effectiveness.

💡 Bonus tip:
Horsetail can also be used in decoction (quick extraction by boiling), which extracts silica and alkaloids more quickly.
👉 To be used fresh – not storable unlike the manure.

🧄 Garlic: a formidable natural repellent against garden insects

Garlic is a top ally in the garden! Thanks to its sulfur compounds, garlic acts as a natural repellent against many pests, including aphids, whiteflies, and certain beetles. Here are two simple and effective techniques to take advantage of its insect-repelling properties.


🌿 Technique 1: Garlic infusion for direct spraying

This method helps protect plants by applying a garlic infusion directly to their foliage.

🔧 Required materials:

  • 5 to 6 cloves of garlic
  • 1 liter of water
  • A sprayer

🧪 Preparation steps:

  1. Peel and crush the garlic cloves.
  2. Bring the water to a boil, then reduce to low heat. Add the garlic and let steep for 10 to 15 minutes.
  3. Let cool, then strain to remove the pieces of garlic.
  4. Pour the infusion into a spray bottle.
  5. Spray on the leaves, stems, and areas affected by insects (including the undersides of leaves).

💡 To be renewed every 4 to 5 days in case of persistent infestation.


🌬️ Technique 2: Olfactory barrier made of garlic, lemongrass, and vinegar

This version acts as a preventive barrier by emitting an unpleasant odor for insects, without directly treating the plants.

🔧 Required materials:

  • 5 cloves of garlic
  • 1 liter of water
  • 1 tablespoon of lemongrass essential oil
  • 2 tablespoons of white vinegar or cider vinegar
  • A sprayer

🧪 Preparation steps:

  1. Prepare a garlic infusion as in the first method.
  2. Once cooled, add the lemongrass oil and the vinegar.
  3. Mix well, then pour into a spray bottle.
  4. Spray around cultivated areas or at the entrance of greenhouses, without directly watering the plants.

💡 Ideal for protecting crops preventively, especially indoors or in greenhouses.


🧼 Black soap spray

Black soap is a timeless grandmother's remedy for eliminating harmful insects. It is a natural soap (soft soap made from vegetable oils and potash) that is diluted in water and sprayed on infested plants.

🔬 Action: Black soap acts by direct contact:

  • It wets and strips the fine protective greasy layer of insects, causing them to dry out.
  • It forms a sticky film that obstructs their respiratory pathways (spiracles).

🪲 Effective against:
Aphids, whiteflies, scale insects, thrips, mites, psyllids…
These soft-bodied insects are quickly eliminated by a black soap treatment.

🌱 Usage:

  • Dilute liquid black soap in warm water (~5 tablespoons per liter of water, or follow the product instructions).
  • Once cooled, spray this soapy water on and under the leaves, making sure to target the colonies of pests.
  • You can also soak a cloth in this solution and manually clean the affected leaves (useful against mealybugs that adhere to the stems).

💡 Note:
Black soap can be used both indoors (houseplants, greenhouses) and in the garden. It is biodegradable and safe for the user, pets, and plants – if used properly.

🎯 Targeted Ravagers:

  • Aphids of all kinds
  • Aleyrodidae (whiteflies)
  • Scale insects (including mealybugs)
  • Thrips (adult and larval forms)
  • Mites (red spiders)
  • Psyllides

Limits:

  • No effect on insects hidden in the tissues (e.g.: leaf miners)
  • Ineffective on hard-shelled insects (adult beetles, adult butterflies)

🔁 Effectiveness and frequency:

  • Shock treatment but short duration, without insecticide residue
  • May require several passes
  • In case of significant infestation:
    • Spray for 2 to 3 consecutive days
    • Then 1 time/week until disappearance
    • Rinse the plant with clear water between applications (to remove debris and sticky honeydew)

⚠️ Precautions:

  • Always test the solution on a small part of the plant (some ferns, orchids, succulents are sensitive)
  • Do not apply in direct sunlight or in high heat (magnifying effect)
  • Process at the end of the day
  • Indoors, you can rinse the foliage a few hours later to avoid sticky deposits.
  • Black soap does not spare beneficial insects if they are present during spraying:
    • "Do not treat when there are ladybugs 🐞 or other allies"
    • Or isolate the plant to be treated

🛢️ Natural oils (Neem oil and essential oils)

Vegetable insecticidal oils form another category of organic treatments.

  • The most well-known is neem oil, extracted from the seeds of the neem tree (Azadirachta indica), renowned for its broad-spectrum insecticidal power.
  • Other essential oils (EO) obtained by distillation of aromatic plants can also serve as insect repellents or natural insecticides: mint, lavender, geranium, citrus 🍋, tea tree, etc. They often act through their powerful scent or by compounds that disrupt pests.

🌿 Neem Oil

It is a plant-based pesticide that has been used for over a century to protect crops.

🧪 Active ingredient:

  • The azadirachtin it contains disrupts the growth and reproduction of many insects.

🎯 Effective against:

  • Aphids
  • Aleurodes
  • Thrips
  • Dust mites
  • Caterpillars
  • Cicadelles
    (And other garden pests)

She also acts as:

  • Anti-feedant
  • Endocrine disruptor
  • With a moderate antifungal action as well.

🌱 Usage:

  • Mix a few milliliters of Neem oil with warm water.
  • Add a little black soap or Marseille soap to emulsify.
  • Spray on the foliage, on the top and bottom of the leaves.
  • Preferably treat in the evening
  • Repeat every 7 to 10 days if necessary (progressive effect)

⚠️ Precautions:

  • Shake the mixture well before use, as the oil separates quickly.
  • Do not overdose: a concentration of 0.5 to 2% is sufficient.
  • Do not apply in direct sunlight
  • Although considered safe for mammals, it is recommended to:
    • Wash treated vegetables before consumption
    • Wear gloves during preparation

🌼 Essential oils (EO)

Many THEY possess insect-repellent or insecticidal properties thanks to their volatile active ingredientsHere are some examples:

  • 🌿 Peppermint essential oil
    Insecticide and repellent recognized against the aphids and other garden insects.
    Son powerful menthol scent disturbs the aphids and can even limit their installation on the neighboring plants.

  • 🍊 Sweet Orange Essential Oil
    Very effective for repelling the whiteflies and the red spiders, thanks to the limonene that it contains.

  • 💜 Essential oil of Lavender (or Lavandin)
    Traditionally used for keep away aphids and ants, particularly around the rose bushes.

  • 🌺 Rose Geranium Oil
    Contains geraniol a you citronellol, compounds effective against scale insects and aphids.
    It is a natural insecticide that can kill these pests by ingestion and inhalation of its volatile compounds.

  • 🌳 Tea Tree Oil (Tea Tree)
    Mostly antifungal, son camphor smell may also displease insects and sanitize the affected plants of cochineals or mushrooms.


🧴 Use of essential oils

⚗️ Important: Never use pure essential oils, they can burn plants.

🧪 Basic Recipe:

  • Dilute 5 to 10 drops of the chosen essential oil (or a blend of several complementary essential oils) in 1 liter of water.
  • Add 1 to 2 drops of black soap or dishwashing liquid as an emulsifier.
  • Shake well
  • Spray on the infested plants, targeting the hotspots (aphids, scale insects...)

🕐 Ideal moment:

  • Since the HE are very volatile, it is preferable to handle them in the evening or early in the morning.
  • Renew 3 days later, then every week as needed.

⚠️ Precautions:

  • Wear gloves and avoid breathing the mixture directly.
  • Essential oils can be irritating to the skin or the respiratory tract.
  • Do not treat in the presence of bees 🐝 (some essential oils like mint can also repel them)
  • Avoid prolonged use of the same essential oil to prevent stressing the plant.
  • Always check that the chosen essential oil is not phytotoxic to your plant species.
    👉 Do a preliminary test on a few sheets

🧪 Decoctions and macerations of plants

(Tomato, rhubarb, tansy…)

In addition to garlic (already discussed in the article), many garden plants can be used to make homemade insecticidal preparations. These decoctions, infusions, or macerations allow for targeting specific pests with local natural resources. Here are three effective recipes:


Tomato leaves

The stems and leaves of the tomato contain tomatine, an alkaloid with insecticidal properties.

💧 Possible preparations:

  • Tomato purée (fermented maceration of the gourmands)
  • Tomato leaf decoction

🎯 Effectiveness:

  • Natural repellent and insecticide
  • Allows to get rid of certain pests:
    • Cabbage butterfly (butterfly and caterpillars) 🦋
    • Altises (small jumping beetles) 🪲
    • Leek moth
    • Carrot fly 🥕
    • And acts by contact on the aphids

🛠️ Usage:

  1. Boil 500 g of tomato leaves in 5 L of water
  2. Let steep while cooling
  3. Filter
  4. Spray the cold and pure decoction on the infested plants (e.g., colonies of aphids)

Tip:
One can add a spoonful of black soap and a little 70° alcohol to improve adhesion and enhance effectiveness.

⚠️ Warning:
The tomato is part of the Solanaceae family and contains potentially toxic alkaloids:

  • Wear gloves during preparation
  • Avoid consuming untreated vegetables without prior washing.

🍃 Rhubarb leaves

The large rhubarb leaves, inedible for humans (toxic due to oxalic acid), can become a formidable natural insecticide.
A rhubarb purée (or a 24-hour maceration followed by a decoction) is used as a non-diluted spray as an insect repellent at the arrival of the first pests.

🎯 Target:

  • Aphids (black bean aphid, green rose aphid, etc.)
  • Parasitic flies (carrot, onion)
  • Leek moth
  • Slugs 🐌

Usage :

  1. Soak ~500 g of chopped leaves in 5 L of water for 24 hours.
  2. Boil for 20–30 min
  3. Let cool, filter
  4. Spray directly on the affected plants (e.g., infested roses)

⚠️ Precautions:

  • Wear gloves (do not rub your eyes during preparation)
  • Do not water the edible soil with this preparation (oxalic acid can disrupt the microbial life of the soil)
  • Don't keep it too long: the manure is more effective fresh.

🌼 Tansy (Tanacetum vulgare)

Tansy is a wild plant with yellow flowers, known for its repellent properties.
"It contains thujones and other powerful aromatic compounds, released in infusion or manure."

🐜 Effective against:

  • Ants
  • Aphids
  • Flies (carrot, onion)
  • High prices
  • Aleurodes
  • Dust mites
  • And more...

🌱 Tip:
Dispersing cut tansy between rows of vegetables helps to disrupt insect detection.

💧 Action insecticide :
A concentrated infusion of tansy can inhibit egg-laying and block the larval development of certain pests:

  • Colorado beetles 🪲 (beetles of potatoes)
  • Carpocapsa (fruit worms)
  • Cabbage Whites 🦋

Usage :

  • Infuse 300 g of fresh tansy (leaves + flowers) in 1 L of boiling water for 24 hours.
  • Or let it ferment for 1 week in manure.
  • Dilute 10–20 % spray on the plants
  • You can also place bouquets of tansy at the foot of fruit trees 🍏 to protect them during pest flight periods.

⚠️ Precautions:

  • Tansy can be irritating to the touch ➤ wear gloves when harvesting
  • Its effect is mainly repellent, complementary to other methods (e.g.: traps or trap plants)

🐞 Beneficial insects (biocontrol allies)

A ladybug eating aphids is a valuable natural ally against infestations!

🌿 Rather than killing pests directly, an ecological approach involves introducing their natural enemies to do the work for you. These organisms are called beneficial insects or crop auxiliaries.

  • Outdoors: encourage their natural arrival with flowering areas, hedges, insect hotels, wild corners.
  • Indoors / greenhouse: specific auxiliaries can be purchased and introduced on infested plants.

🐞 Ladybugs (and their larvae)

Ladybugs are great aphid eaters.
The seven-spotted ladybug is well known: a single adult or larval individual can consume up to 100 aphids per day.
"They also sometimes attack other small insects such as scale insects or psyllids."

Usage :

  • In the garden, attract them naturally with nectar-rich flowers 🌸
  • Avoid pesticides
  • In case of an invasion, you can buy larvae and place them on the infested plants – they will get to work immediately!

⚠️ Precautions:

  • Release them in the evening or early in the morning.
  • Lightly mist the plants before ➤ they will drink and stay more willingly.
  • Indoors, once they are adults, ladybugs may try to get out ➤ use them mainly in a closed greenhouse.

🌿 Chrysopes (Chrysoperla carnea, "golden-eyed lacewing")

Chrysopid larvae are voracious predators, capable of eating:

  • 50 aphids per day
  • But also thrips, small caterpillars, whiteflies...

👉 They are nicknamed "aphid lions".

Usage :

  • You can buy eggs or larvae.
  • Drop them in infested areas (garden or greenhouse)
  • Adults become pretty green insects and feed on pollen (harmless)

⚠️ Precautions:

  • Green lacewings are nocturnal ➤ don't be surprised if you don't see them during the day.
  • "Do not apply either black soap or oil in the areas where you have released them, or you risk killing them."

🕷️ Predatory mites – Specialists in spider mites and thrips

These are tiny carnivorous mites (e.g.: Phytoseiulus persimilis, Amblyseius swirskii) that feed on other mites or insects.
They are the natural enemies of spider mites (red spiders) and they also attack thrips.

Usage :

  • They are mainly introduced in greenhouses or indoor cultivation.
  • "We buy packets or tubes containing these live mites."
  • They are dispersed on the infested plants, where they actively seek out the harmful colonies to devour.
  • Some like A. swirskii can be used as a preventive measure against thrips and whiteflies.

⚠️ Warning:

  • These mites like a certain humidity.
    ➤ If the air is too dry (< 50%), mist the foliage a little.
  • Avoid sulfur or oil treatments, which are harmful to them.

🛡️ Predatory bugs – Against thrips, whiteflies, caterpillars

Small carnivorous bugs like Orius laevigatus (the "pirate bug") or Macrolophus are used in greenhouse crops to regulate:

  • Les thrips
  • Whiteflies
  • The caterpillars
  • And sometimes even the dust mites

🔬 They sting and empty their prey 🧪

Usage :

  • Often used by professional market gardeners, but also suitable for the amateur gardener in a greenhouse.
  • Introduce them as soon as the first thrips are spotted.
  • Orius is also effective on indoor plants.

⚠️ Warning:

  • These bugs can fly.
    ➤ Outside, they might leave.
    ➤ In a greenhouse, they remain in the closed ecosystem.

🪱 Entomopathogenic nematodes – Trap soil pests

They are not insects, but microscopic beneficial worms (genus Steinernema or Heterorhabditis) that parasitize insect larvae in the soil.

🎯 Main targets:

  • Gray worms (moth larvae, caterpillars in the soil)
  • Soil fly larvae (sciarids)
  • Pupal stages of thrips fallen to the ground
  • White lines on grass
  • From the ground to the vegetable garden

Usage :

  • Buy a bag of live nematodes (in powder form to dilute)
  • Water the infested soil with this solution.
  • Nematodes enter insect larvae and eliminate them.

⚠️ Precautions:

  • Respect the temperature and humidity conditions (in general:
    ➤ sun > 12°C,
    ➤ end-of-day processing,
    ➤ wetland)
  • Nematodes are harmless to the environment, except for targeted insects.

🐝 Other useful natural allies

Other auxiliaries also deserve to be mentioned:

  • Syrphus 🪰: their larvae eat aphids
  • Parasitoid Wasps 🐝 :
    • Encarsia formosa against whiteflies in greenhouses
    • Trichogramma against the eggs of pest butterflies
  • Insectivorous birds 🐦 : love caterpillars in gardens

⚠️ General precautions with auxiliaries

If you introduce beneficial insects, here are some recommendations to not compromise their effectiveness:

🚫 Avoid insecticide treatments, even organic ones (black soap, oils…), just after introduction ➤ this could kill your allies.
✔️ Apply these treatments before their arrival, then let them act naturally.

💧 Provide a welcoming habitat:

  • Leave some aphids on an isolated plant to feed the ladybugs.
  • Maintain good humidity for predatory mites
  • Plant nectar and pollen-rich flowers 🌼 to feed the adults of many beneficial insects (ladybugs, lacewings, hoverflies…).

🌿 Result: your auxiliaries will establish themselves sustainably and will prevent the return of pests in a natural and effective way.


🐛 Summary table: Common pests & natural solutions (Prevention – Treatments – Beneficials)

Pest

Prevention 🌱

Natural treatment 🧴

Auxiliary insects 🐞

Notes / Tips 💡

Aphids

- Companion plants (garlic, mint, onion, chives, nasturtium as a trap plant)
- Balanced mulching
- Avoid excess nitrogen

- Nettle manure
- Black soap spray
- Essential oils (geranium, lavender)
- Tomato infusion

- Ladybugs (larvae & adults)
- Chrysopes
- Syrphes

"Manually remove the colonies at the beginning. Monitor the underside of the leaves." 🌿

Aleurodes
(White flies)

- Basil, marigolds
- Ventilation, aeration
- Yellow sticky traps

- Black soap
- Neem Oil
- Tansy infusion

- Beautiful Encarsia (parasitoid wasp)
- Macrolophus
- Amblyseius swirskii

Prefer warm & dry climates. Likes stressed plants.

Thrips

- Sticky blue traps
- Mist generation for humidity
- Crop rotation

- Neem Oil
- Black soap
- Essential oils (peppermint, sweet orange)
- Garlic decoctions

- Smooth-billed Orius
- Chrysopes
- Amblyseius swirskii
- Nematodes

Very small, difficult to spot. Attack the young shoots.

Red spiders
(Mites)

- Increase humidity
- Regular misting
- Active ventilation

- Horsetail manure
- Neem Oil
- Black soap

- Phytoseiulus persimilis
- Amblyseius californicus

Very sensitive to humidity. Do not treat in direct sunlight. ️.

Caterpillars

- Protective nets
- Crop rotation
- Capucine egg trap

- Manual collection
- Tomato manure
- Rhubarb decoction

- Trichogrammes (egg parasites)
- Insectivorous birds (outdoors)

Carefully inspect the underside of the leaves. Look for eggs and young caterpillars. 🥬

Scale insects

- Regular inspection
- Avoid accumulation of dust on leaves

- Hot black soap
- 90° alcohol localized
- HE of geranium or lavender

- Cryptolaemus montrouzieri (carnivorous ladybug)

Indoors, they are very tenacious. Clean the sticky leaves.

Ants

- Remove aphids (their source of honeydew)
- Tired of coffee at the foot
- Cinnamon around the jars

- Lemon juice
- Natural barriers (chalk, bicarbonate)

"They are not direct pests, but they raise aphids!" 👀

Fungus gnats
(sciarides)

- Well-drained substrate
- Moderate watering
- Dry mulching (clay balls)

- Nematodes (Steinernema feltiae)
- Drying of the soil
- Yellow traps

- Entomopathogenic nematodes

Often indoors. They develop if the substrate is too moist. 🪴

 

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