Jap beetle 1 MER copy.jpg

Japanese beetle grub


  • Adult: Metallic green beetle with bronze wing covers about ½" long. There are six tufts of white hair on each side of the abdomen just below the wing covers.
  • Larvae: Grubs are creamy white with a brown head capsule, C-shaped and about 1" long.
  • Eggs: White to translucent, small and elliptical to spherical in shape. 

Timing of damage: V8 to R6

Type of damage: Adults feed on silk and leaves, causing skeletonized defoliation. Grubs feed on 
corn roots.

Scouting: Check five plants in each of five locations of a field and note the number of beetles and the extent of silk clipping.

Economic threshold: When silks are cut to less than ½", less than 50% of the field has been 
pollinated and beetles are present and feeding.

Similar Pests

Ask an Agronomist