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Section 26.6.2: Japanese Beetle

Popillia japonica

Time of concern: Late June through August. During ear formation when adults move from other crops into corn.
Key characteristics: The adult stage is the damaging stage on corn. The adults are metallic green or greenish brown beetles about 1/3 to 5/8 inches in length, with reddish wing covers. They feed on a wide range of agricultural and landscape plants and are a major pest of turf. In areas where it is abundant, it can cause severe damage to corn by feeding on the husks, foliage, kernels, and silk.

Japanese Beetle

Management Option Guideline

There are no formal thresholds for this pest on corn. Regular scouting, especially during ear formation, is needed.

Natural enemies

While the area-wide population of Japanese beetle is regulated by natural enemies during its larval stage, when the adults move into corn they are not readily subject to natural enemies except birds. 

Resistant varieties No resistant varieties are available.
Crop rotation This is not a viable management option
Insecticide Resistance Management

The Insecticide Resistance Action Committee (IRAC) has classified insecticides into resistance management groups. Most insecticides include an IRAC group number on the front page of the label. Alternating between insecticides with different group numbers will help avoid the development of resistant insect populations.

Site selection, Post-harvest, and sanitation Because the Japanese beetle larvae live in the soil and emerge in mid-summer, planting corn to avoid times of adult emergence will be helpful. See your Cornell Cooperative Extension Office for information about times of adult emergence in your particular area.
Pesticides Cornell Integrated Crop and Pest Management Guidelines for Commercial Vegetable Production