Ten-lined June beetle

The ten-lined June beetle (Polyphylla decemlineata) is a prominent member of the Scarabaeidae family, belonging to the order Coleoptera. Native to western North America, this species is well-recognized by the characteristic white stripes along its elytra. While adults are often observed around lights at night, the larval stage is where the primary economic damage occurs.

The larvae, often referred to as white grubs, are soil-dwelling insects that feed on the root systems of a wide variety of plants. Their host range is extensive, including strawberries, potatoes, ornamental trees, and various grasses. By consuming roots, they interrupt the plant's ability to take up water and nutrients from the soil.

The life cycle of the ten-lined June beetle is complex and typically lasts three to four years. The female beetle deposits eggs deep in the soil. Upon hatching, the larvae undergo multiple molts, growing significantly in size each year. They often migrate deeper into the soil profile to survive freezing winter temperatures before returning to the root zone in the spring.

The damage caused by these grubs is often catastrophic to young plants, such as tree seedlings or nursery stock. Infested plants typically show signs of wilting, chlorosis, and eventual death. Because the grubs feed underground, the damage is frequently hidden until it is too late to rescue the plant, making early identification and soil monitoring critical for management.

Management strategies for the ten-lined June beetle involve several key approaches:

• Cultural control: Frequent soil cultivation to expose larvae to birds and predators.
• Biological control: Use of entomopathogenic nematodes or fungi.
• Chemical control: Application of granular insecticides into the soil during planting.
• Monitoring: Using light traps for adults to predict population levels in the coming seasons.