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Pests on Plants

Identification, Damage and Effective Control
Pests represent a recurring risk in interior landscaping and project planting. Without timely intervention, a minor infestation can gradually develop into visible damage, growth delay and increased maintenance costs, directly impacting plant quality. Koberg supports you by helping identify pests at an early stage, prevent infestations effectively and apply targeted control measures. This guide provides an overview of the most common pests, including clear identification characteristics, damage symptoms and proven control methods, enabling you to maintain control over the health, appearance and continuity of your planting projects.

Aphids

Identification
Aphids are small, soft-bodied insects that mainly gather on young shoots and the underside of leaves. They occur in various colours, such as green, black and yellow, and are usually visible to the naked eye. Aphids often form dense colonies, which accelerates their spread. A common additional indicator is the presence of white shed skins on the leaves.
Damage
Leaves may curl, yellow or droop as aphids extract plant sap. In addition, they excrete honeydew, resulting in sticky leaves and the development of sooty mould. Plant growth can visibly slow down.
Control
Affected plants can be rinsed with water. Insecticidal soap or green soap is an effective follow-up treatment. Natural enemies such as ladybirds and lacewings contribute to sustainable control.

Scale Insects

Identification
Scale insects are small insects covered with a hard or waxy shield. They attach themselves to stems, leaf veins and leaf axils and hardly move. Due to their fixed position, they are often noticed only at a late stage. Sticky honeydew is frequently the first indirect sign of infestation.
Damage
The plant weakens as scale insects continuously extract sap. Leaves may discolour or fall prematurely. Prolonged infestation reduces overall plant vitality.
Control
Manual removal using alcohol or oil is effective in cases of light infestation. Soap- or oil-based treatments help suffocate the insects. Severely affected plant parts are best pruned and removed.

Fungus Gnats

Identification
Fungus gnats are small black flies that are visible around the potting soil. They often emerge when plants are watered or moved. Adult flies are short-lived but lay eggs in moist soil. The larvae live in the upper layer of the substrate.
Damage
Larvae can damage root hairs, especially in young or weakened plants. This disrupts water and nutrient uptake, leading to growth retardation or wilting.
Control
Allow the potting soil to dry out more between watering. Yellow sticky traps help monitor adult flies. Beneficial nematodes are effective against larvae in the soil.

Spider Mites

Identification
Spider mites are extremely small and difficult to see directly. They mainly occur on the underside of leaves. An early symptom is the appearance of fine, pale speckling on the leaf surface. At a later stage, webbing becomes visible between leaves and veins.
Damage
Spider mites suck out cell contents, causing dull discolouration. Leaves may dry out and drop prematurely. In severe infestations, the plant rapidly loses vitality.
Control
Increase humidity and regularly mist plants. Treatment with neem oil or green soap can provide support. Predatory mites offer an effective biological solution.

Thrips

Identification
Thrips are slender, fast-moving insects that often hide in leaf axils. They are usually brown, black or yellow in colour. Their presence is often indicated by silvery streaks or spots on leaves, caused by their scraping and sucking feeding behaviour.
Damage
Leaves and flowers may deform or discolour. Affected cells die off, reducing ornamental value. Prolonged infestation weakens the plant.
Control
Yellow sticky traps assist with monitoring. Natural control products or soap solutions reduce population levels. Biological predators such as predatory mites enhance effectiveness.

Whiteflies

Identification
Whiteflies are small white insects that mainly reside on the underside of leaves. When disturbed, they fly up in large numbers. Eggs and nymphs are often present on the same leaf. Infestations develop particularly in warm, sheltered environments.
Damage
Sap extraction leads to yellowing and reduced growth. Honeydew causes sticky leaves and promotes mould growth. Leaves may curl or drop.
Control
Yellow sticky traps are used to capture adult insects. Treatment with a soap solution can reduce infestation levels. Regular monitoring is essential.

Mealybugs
Identification
Mealybugs are recognisable by their white, cotton-like deposits. They are often found in leaf axils and along stems. Their waxy protective layer makes them clearly visible. They usually occur in clusters.
Damage
Continuous sap extraction weakens the plant. Leaves may turn yellow and become limp. Honeydew causes sticky residues and mould formation.
Control
Removal with alcohol is effective for light infestations. Insecticidal or green soap supports further control. Repeated treatments are important.

Black Vine Weevil
Identification
Half-moon-shaped notches along leaf edges often indicate the presence of black vine weevils. Adult beetles are mainly active at night and hide in the surrounding area during the day. Larvae live underground.
Damage
Adult beetles cause leaf damage, but larvae inflict the most serious harm by feeding on roots. This can result in wilting and plant loss. Damage often remains unnoticed for a long time.
Control
Manual removal of adult beetles helps limit population growth. Beneficial nematodes are effective against larvae in the soil. Ongoing monitoring is crucial.

Box Tree Moth
Identification
The box tree moth is identified by green caterpillars within webbing inside the boxwood plant. Webbing and feeding damage are clear indicators. The pest mainly occurs during the growing season.
Damage
Caterpillars consume leaves and young shoots, quickly resulting in a bare and weakened plant. Without intervention, boxwood plants may die.
Control
Manually remove caterpillars in cases of light infestation. Biological agents such as Bacillus thuringiensis are effective. Regular inspection prevents escalation.

Elaeagnus Psyllid
Identification
The elaeagnus psyllid is a small, jumping insect that moves quickly and is mainly found on young leaves. Infestation is noticeable through leaf deformation. Honeydew may also be present.
Damage
Leaves become misshapen and discoloured, reducing the plant’s ornamental value. Prolonged infestation weakens growth.
Control
Affected plant parts can be rinsed with water. Natural control products help reduce population levels. Preventive monitoring is recommended.

Leatherjackets
Identification
Leatherjackets are the larvae of crane flies and live in the soil. They are grey-brown and legless. Adult crane flies are often seen in autumn. Damage usually becomes visible at a later stage.
Damage
Leatherjackets feed on roots, leading to wilting and plant loss. Grass or plants may loosen in the soil. Birds feeding on the larvae can cause additional damage.
Control
Beneficial nematodes are effective against leatherjackets. Soil improvement and maintaining strong plant health reduce the risk of reinfestation. Prevention plays a key role.