May beetle

Systematic position. The May beetle (Lachnosterna, often associated with the genus Melolontha) belongs to the order Coleoptera and the family Scarabaeidae. These insects are well-known as significant pests in forestry and agriculture, recognized primarily for the extensive damage caused by their larvae in the soil.

Affected crops. Adult beetles feed on the foliage of various deciduous trees and shrubs, including apple, cherry, and walnut trees. However, the larvae, commonly known as white grubs, are more destructive. They feed on the root systems of a wide range of plants, including potatoes, strawberries, vegetables, and young nursery saplings.

Biology and life cycle. The life cycle of the May beetle is relatively long, typically spanning three to five years, with most of this time spent in the soil. Females deposit eggs in soft, organic-rich soil. Upon hatching, the larvae go through several developmental stages. While early-stage larvae consume organic matter, older larvae feed aggressively on living plant roots, causing severe damage.

Nature of damage and harmfulness. The primary economic damage is caused by the larvae severing plant roots, which prevents water and nutrient uptake. This leads to wilting and eventual death of the affected crops. Adult beetles can cause secondary damage by defoliating trees, which significantly reduces plant vigor and long-term productivity, especially in young orchards.

Protection measures. Effective control requires an integrated approach to pest management:

• Mechanical soil cultivation, such as plowing or tilling, which exposes larvae to predators and environmental stress.
• Application of biological control agents, such as entomopathogenic fungi (e.g., Beauveria bassiana), to infest the soil.
• Using soil-applied insecticides during planting to provide a protective zone for root systems.
• Crop rotation and planting non-host cover crops, such as mustard, to minimize infestation risk.