T
he Japanese beetle (Popillia
japonica) was introduced to the
Unit ed States around 1916 on nursery
stock. Since its introduction, this exotic
invasive insect has established in
almost every state in the eastern half of
the country.
Nebraska is on the leading edge of
this infestation as the beetle moves
westward. Currently 38 Nebraska
counties are considered infested,
including Douglas and Sarpy counties
where infestations are widespread.
Adult beetles are approximately
½-inch in length. The head and thorax
are green and the elytra (hard back
wings) are brownish to bronze in color.
June beetles, by comparison, are larger
in size and a more uniform orange to
dark brown color.
Other scarab species, including the
false Japanese beetle and the rose
chafer, both of which are found in
Nebraska, are often confused with the
Japanese beetle. A key identification
characteristic of the Japanese beetle is
the white tufts of hairs on the sides and
end of the adult abdomen. Japanese
beetles have a one-year life cycle.
Adult females begin to lay eggs in
the ground in early to mid-summer.
White grubs, similar to the grubs of
other scarab beetles, hatch from these
eggs. The grubs (larvae) remain in the
soil, feeding on grass roots, which can
cause significant damage to turfgrass.
Grubs overwinter by burrowing deep
into the soil. As spring approaches and
soil temperatures increase, the grubs
resume feeding, then pupate before
emerging as adults. In Nebraska, adult
emergence typically begins in early to
mid-June.
Adults crawl out of the ground and
begin to feed on flowers and foliage.
Preferred hosts include linden, rose
and grapes, but these insects are known
to feed on more than 300 species of
plants, ranging from trees and shrubs to
annuals and vegetables.
Homeowners and land managers
have a number of chemical options for
managing Japanese beetles. Selecting
plants that are less attractive to adult
beetles and hand removing adults
(when populations are low) are non-
chemical options. Contact your local
extension office for Japanese beetle
management recommendations. ■
By Julie Van Meter
State Entomologist,
Nebraska
Department
of Agriculture
JUNE 2018 • NEBRASKAland 17
Bug Banter
Japanese Beetle.
PHOTO COURTESY OF DAVID CAPPAERT,
BUGWOOD.ORG.
Japanese Beetle.
PHOTO COURTESY OF DAVID CAPPAERT, BUGWOOD.ORG.
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