Insect
Japanese Beetle
Popillia japonica
Biology
The Japanese beetle, Popillia japonica Newman, is an invasive and highly polyphagous scarab beetle within the family Scarabaeidae. Adults are approximately 8-11 mm long, with iridescent metallic-green bodies and copper-brown elytra. Five tufts of white hair project from under the elytra on each side of the abdomen. Females lay 40-60 eggs individually in the soil, which hatch into C-shaped white grubs that feed on plant roots. Larval development involves three instars. The life cycle is typically univoltine, requiring one year to complete, with grubs overwintering in the soil. Optimal soil moisture and temperatures around 20-250C promote successful egg and larval development.
Behaviour
Adult Japanese beetles are highly active during warm, sunny days, skeletonizing leaves, fruits, and flowers. They exhibit strong aggregation pheromone responses, leading to large congregations on preferred host plants, intensifying damage. Females prefer to lay eggs in moist, well-draining soil, particularly in turfgrass. Larvae, or grubs, remain subterranean, feeding on roots. Adults are strong fliers and can disperse rapidly, contributing to their spread. When disturbed, adults may drop from plants.
Habits
Japanese beetles infest a vast array of over 300 plant species, including roses, grapes, maples, and turfgrass. Adults are found on plants, feeding voraciously. Grubs are found in the soil of lawns, golf courses, and pastures, causing damage by severing roots, leading to brown, dying patches of grass. Conducive conditions include well-maintained turf for egg-laying and warm, moist soil for larval development. Areas with a diverse range of host plants are particularly susceptible to severe infestations.
Control methods
- 1Hand-pick beetles in small infestations.
- 2Use pheromone traps for monitoring.
- 3Apply milky spore disease to laws.
- 4Introduce parasitic nematodes to soil.
- 5Apply preventative grub control early.
- 6Use contact insecticides on foliar pests.
Tailored to Japanese Beetle
IPM Procedure Checklist
Inspection
- Inspect harborage near food, water and warmth
- Check cracks, voids and appliance interiors
- Place sticky monitors at suspected hot-spots
Identification
- Confirm Japanese Beetle (Popillia japonica) — not a look-alike
- Note life stage and risk level: Moderate
- Capture clear photos and samples for the record
Action Thresholds
- Trigger action when monitor counts trend up
- Re-evaluate weekly during active season
- Document trigger criteria in the IPM plan
Prevention
- Seal cracks, plumbing penetrations and wall voids
- Eliminate moisture sources and standing water
- Improve sanitation: sealed food storage, grease removal
Control Methods
- Hand-pick beetles in small infestations.
- Use pheromone traps for monitoring.
- Apply milky spore disease to laws.
- Introduce parasitic nematodes to soil.
Monitoring & Evaluation
- Service monitors on schedule and trend captures
- Re-inspect for Japanese Beetle activity at follow-up
- Adjust tactics based on data; report findings to client