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Symptoms and Impact on Crop

Japanese beetles feeding on corn
Japanese beetle on corn leaf
  • Clipped corn silks from the Japanese beetle may reduce pollination and yield
  • Skeletonized or lacy leaf patterns between veins are symptoms of either corn or soybean feeding
  • Leaf feeding is typically insignificant in corn
  • Leaf feeding may be more significant in soybeans, causing defoliation prior to pod fill

Pest Facts

Japanese Beetle
  • Latin name is Popillia japonica
  • Native to Japan; found in United States in 1916
  • Most damage is from adult feeding; however, the larval grub also can feed on roots
  • Late-planted fields are at greater risk
  • Japanese beetles are often found in field edges or areas of delayed growth
  • Over 300 hosts: corn, soybean, ornamentals, fruit trees, grapes, weeds
  • One generation per year

Distribution

Japanese beetle distribution map (U.S.)
  • Well established east of the Mississippi River, the Japanese beetle is also present in most other corn and soybean growing states

Pest ID

Key Characteristics

Japanese Beetle

Japanese Beetle

  • One-half inch adults are shiny metallic green with bronze wing covers, with six white hair tufts on each side of their abdomen

 

Related Species

Masked Chafer

Masked Chafer - light color

Green June Beetle

Green June Beetle - twice the size, no white tufts

False Japanese Beetle/Sand Chafer

False Japanese Beetle/Sand Chafer - dull, no white tufts

Life Cycle

Japanese Beetle Annual life cycle

Japanese Beetle Management

  • Favorable conditions
    • Adults prefer lighter soil for egg laying
    • First entry into an area is usually near transportation such as railroads or major highways
  • There are no natural enemies in the U.S.
  • IPM Practices
    • No transgenic or native gene resistance is currently available for either soybeans or corn
    • Trapping is NOT recommended as it has a tendency to attract the beetles
    • Scouting should begin in corn in July and August and switch to soybeans during August
    • Use percent pollination and presence of uncut silks as a guide when deciding treatment of corn. Leaf feeding is rarely significant in corn.
    • Use percent defoliation and amount of pod fill remaining to help decide economics of insecticide treatment for soybeans

Economic Thresholds

  • Treatment thresholds for corn insecticides:
    • Silks clipped to within ½ inch of the ear tip
    • Less than 50% of plants pollinated
    • Beetles are present and feeding

The foregoing is provided for informational use only. Please contact your Pioneer sales professional for information and suggestions specific to your operation. Product performance is variable and depends on many factors such as moisture and heat stress, soil type, management practices and environmental stress as well as disease and pest pressures. Individual results may vary.