Insects – Japanese Beetles

Biology

Japanese beetles (Popilla japonica) are an invasive pest in North America, first introduced from Japan in 1913.  Japanese beetle adults are extremely polyphagous, feeding on over 300 plants.  Japanese beetle larvae feed underground on the roots of grasses and weeds.  They are a minor pest of tobacco, feeding on leaf tissue with 1 annual generation in North Carolina.

Because their larvae feed underground, Japanese beetles are sensitive to soil moisture and populations are lower in seasons following droughty years

Management and Thresholds

No exact thresholds for Japanese beetles have been established, but as a rule, treatment is recommended when anticipated damage is equal to or greater than that caused by a 10 percent budworm infestation.

Broad spectrum insecticides are effective against Japanese beetles, but organic options are limited and variable in their effectiveness. 

See the North Carolina Agricultural Chemicals Manual for registered materials, rates, and applications recommendations.

Biological Control

Biological control agents against Japanese beetles include milky spore (Bacillus popilliae), a bacterial pathogen, and the spring wasp (Tiphia vernalis).  Both these biological controls target the larvae, which because they feed on the roots of grasses and weeds will not present in tobacco fields.  While soil treatment or ground cover manipulation may be beneficial in perennial crop production and over a large area, it is not recommended in tobacco or areas adjacent to tobacco fields.

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