**White Grubs** are the larvae of various scarab beetles (Family Scarabaeidae), including **Japanese Beetles** (*Popillia japonica*), **European Chafers** (*Rhizotrogus majalis*), and **May/June Beetles** (*Phyllophaga* spp.). The conflict is **root destruction of turf and crops**: the grub feeds on the roots of grasses and field crops, leading to large patches of brown, dead turf that can be rolled back like a carpet, or severely damaged root vegetables (potatoes, carrots). They are one of the most destructive soil pests in North America.
Taxonomy and Classification
White Grubs belong to the Order Coleoptera (Beetles). They undergo complete metamorphosis, with the life cycle lasting 1 to 3 years, depending on the species.
Physical Description
Larvae are large, 20 mm to 40 mm long.
- **Larva (Key ID):** Plump, white, soft-bodied grub with a brown head; typically found curled into a distinct **”C” shape** when unearthed; possesses three pairs of legs near the head.
- **Adult (Key ID):** Hard-shelled, large beetles (e.g., Japanese Beetles are iridescent green and bronze).
- **Damage ID (Key):** Irregular patches of dead, brown lawn turf; turf feels spongy and can be easily lifted; presence of feeding tunnels or “frass” near damaged roots.
- **Conflict:** Agricultural, Ornamental (Turf).
Distribution and Habitat
Found worldwide. Habitat is soil, particularly high-organic-matter turf, pasture, and fields growing root crops or corn.
Behavior and Conflict
The conflict is their high consumption rate and density.
- **Grub Migration:** Grubs move vertically in the soil profile in response to temperature (deep in winter, near the surface in spring/fall).
- **Secondary Damage:** Damage is often compounded by vertebrate predators (raccoons, skunks) digging up the lawn to eat the grubs.
Management and Prevention
Management is **Integrated Pest Management (IPM) and Soil Treatment**.
- Application of **entomopathogenic nematodes** (*Heterorhabditis* spp.) or the bacteria **Milky Spore** (*Paenibacillus popilliae*) to the soil.
- Application of preventative (long-residual) or curative (contact) insecticides to the soil, timed to the small, susceptible grub stages.
Conservation and Research
Research focuses on developing low-impact soil insecticides, improving the application of nematodes, and breeding turfgrass varieties that are more tolerant of root damage.