Phyllophaga parallela

Systematic position. This species belongs to the order Coleoptera and the family Scarabaeidae. Phyllophaga parallela is a significant representative of the genus, commonly referred to as May or June beetles. These beetles are primarily known in North and Central America for their complex life cycles and the damage their larval stages cause to various vegetation types.

Affected crops and damage. Adult beetles feed on the foliage of diverse broad-leaved trees, including oaks, maples, and fruit-bearing species. However, the most destructive phase is the larval stage, known as white grubs. These larvae inhabit the soil, feeding voraciously on the root systems of agricultural crops, lawns, and nursery stock, leading to stunted growth, wilting, and plant mortality.

Biology and life cycle. The development cycle of this pest can span several years, depending on the environment. Females deposit eggs in the soil near suitable host plants. Upon hatching, the larvae go through several instars, feeding on organic matter and living roots. The pupation phase occurs within a soil cell, after which the adult beetle emerges to restart the life cycle.

Economic importance. High populations of larvae can cause severe economic losses, particularly in turfgrass and vegetable fields. By pruning the roots, the grubs prevent plants from absorbing water and nutrients efficiently. This makes crops highly susceptible to environmental stress and secondary infections, often resulting in widespread patchiness and reduced yield potential.

Control measures. Integrated pest management (IPM) is essential for controlling this beetle. Key strategies include:

• Tillage practices that physically destroy larvae and expose them to avian predators.
• Application of soil-incorporated insecticides at the time of planting.
• Use of biological controls such as entomopathogenic nematodes (e.g., Heterorhabditis spp.) or fungi.
• Monitoring adult flight periods with light traps to time preventative treatments.