Cockchafer

Taxonomic position: The cockchafer (Melolontha melolontha), often referred to as the May bug, belongs to the order Coleoptera and the family Scarabaeidae. It is recognized as one of the most destructive pests in forestry and horticulture, particularly due to the subterranean activity of its larvae.

Affected crops: Adult beetles feed on the foliage of deciduous trees and shrubs, including fruit species such as apple, pear, and plum. However, the primary economic damage is caused by the larvae, known as "white grubs." These larvae are polyphagous and feed on the roots of vegetables (potatoes, carrots), strawberries, ornamental plants, and young nursery trees.

Biology and life cycle: The life cycle of the cockchafer is long, typically lasting between three and five years. Most of this time is spent underground as larvae. The adults emerge in spring to feed and mate, with females laying eggs deep in the soil. Development progresses through three larval instars, with each subsequent year leading to increased feeding intensity and root damage.

Damage and severity: Larvae are the most damaging stage, as they sever the root systems of crops, causing plants to wilt, stop growing, and eventually die. This often leads to significant crop failure in fields and nurseries. Adults also cause damage by defoliating trees, which weakens the plants and reduces their future yield potential.

Protection measures: Management requires a combination of strategies. Cultivation practices such as deep autumn tillage help expose larvae to predators and environmental stress. Biological control methods, including the use of entomopathogenic nematodes or fungi like Beauveria bassiana, have proven effective. Chemical control involves applying soil insecticides to the root zone to suppress larval populations.

• Deep soil cultivation in autumn.
• Application of entomopathogenic nematodes.
• Using soil-applied insecticides.
• Planting repellent cover crops like mustard.
• Hand-collecting adults during the early morning.