Beetles on plants: how to recognize and treat the damage

Beetle damage to leaves, stems and other parts of the plant

Beetles can cause significant damage by feeding on leaves, shoots, flowers, fruits or even roots, depending on the species. The damage usually appears as bites, holes or areas of consumed tissue and can quickly affect the appearance and development of the plant.

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How to recognize damage caused by beetles

Beetles on plants – damage to leaves and shoots

Leaves and young shoots damaged by beetles

Chewing insects feed directly on plant tissues and can mainly cause damage to leaves, although some species also attack shoots, flowers or fruits. The appearance of the lesions can vary considerably depending on the insect and the intensity of the attack.

The main symptoms are:

• Holes of different sizes in the leaves.

• Leaf edges that have been chewed or have an irregular appearance.

• Areas of the leaves that have been partially eaten.

• Large parts of the leaf that have been completely consumed.

• Perforations that can pass through the entire leaf.

• Young shoots that have been chewed or damaged.

• Flowers with eaten or damaged parts.

• Fruits with bite marks or consumed areas in some species.

• Presence of chewing insects on the leaves, shoots or around the damaged areas.

• Loss of a large part of the leaf surface when the attack is severe.

• Plant weakened and with reduced vigor when the damage is significant.

Do not confuse with snails and slugs

Snails and slugs also produce holes and large eaten areas on leaves. A frequent difference is the presence of shiny slime trails on leaves, stems, pots or soil. They also tend to cause more damage at night, after watering or under very humid conditions.

Do not confuse with caterpillars

Caterpillars are also chewing insects and can produce holes of different sizes and large eaten areas on leaves. In many cases, the caterpillars themselves can be found on the plant, especially on the underside of leaves, between shoots or in protected areas. An unmistakable sign of the presence of caterpillars is the presence of small droppings or dark residues on leaves, fruits or beneath the areas being eaten.

How to treat beetles on plants

When beetles or recent bite marks are detected, acting quickly helps reduce the population and prevent the damage from continuing. Combining the removal of visible beetles with frequent inspection of the plant and an insecticide treatment allows more effective control.

The main recommendations and treatments are:

• Inspect the plant: regularly checking leaves, shoots, flowers and fruits allows beetles and their damage to be detected quickly. It is also important to check the underside of the leaves and the more protected areas, where they may remain hidden.

• Remove visible beetles: when their presence is low, manually removing the specimens helps quickly reduce the population and prevents them from continuing to feed on the plant.

• Remove severely damaged leaves or parts: removing areas with significant damage helps keep the plant clean and promotes its recovery.

• Keep the area clean: removing plant debris and weeds around the plant reduces potential hiding places and makes it easier to detect new specimens.

• Deltamethrin insecticide: it is an effective solution for controlling beetles and quickly reducing the population present on the plant. Deltamethrin acts by contact on the insects’ nervous system, providing direct action against exposed specimens and helping to stop active damage. It is particularly recommended when beetles and recent damage are observed on leaves, shoots or fruits.