JAPANESE BEETLE
James R. Baker and S. Bambara, Extension Entomologists
CAUTION: These recommendations were
developed for North Carolina and may not apply to other areas.
JAPANESE BEETLE, Popillia japonica Newman, Scarabiidae, COLEOPTERA
About
1/2 inch long, Japanese beetles are a shiny, metallic green with coppery
brown wing covers that extend almost to the tip of the abdomen. Small tufts
of white hairs occur at the tip of the abdomen and along each side. Eggs
are translucent white to cream and elliptical and about 1/16 inch in diameter
when first laid. In a few days, the egg becomes more spherical and doubles
in size. Grubs are white, slightly curled and have yellow-brown heads.
Grubs are about 1 inch long when mature. Unlike other grubs found in turf,
it has two rows of spines which form a "V" on the underside of the last
abdominal segment. The pupa is approximately 1/2 inch long and 1/4 inch
wide, and it gradually turns light brown and then develops a metallic green
cast.
Biology
First
reported in North America in 1916, the Japanese beetle now occurs in most of
the eastern United States. The beetles feed on over 275 different kinds of
shade and fruit trees, shrubs, flowers, small fruits, garden crops, and weeds.
Some of their favorites are roses, crape myrtle, grapes and fruit trees. Japanese
beetle adults eat flowers and foliage, leaving only a lacy network of leaf
veins. The beetle grubs are pests of the roots of grasses and shrubs. Japanese
beetle grubs occur in lawns, golf courses, pastures and even wooded areas.
They burrow through the soil consuming roots. Areas of dead grass may appear
when large numbers of grubs are present especially during dry spells in September
or early October. The grubs overwinter in cells about 6 inches deep. In spring,
they move almost to ground level, where they complete feeding and then pupate.
Adults emerge as early as mid May in eastern North Carolina. Peak emergence
occurs in July. Throughout summer, the beetles attack the fruit and foliage
of many plants. Soon after emerging, females deposit 40 to 60 eggs in small
batches 2 to 3 inches deep especially in damp soil. During dry periods,
adults may be more attracted to low lying and irrigated areas to lay eggs where
soil moisture is higher. In extremely dry weather, many eggs and larvae perish.
In warm, wet summers, eggs hatch in about 2 weeks. The newly emerged larvae
feed until cold weather forces them into hibernation. One generation occurs
each year.
Management
Flowers and ornamental plants can be protected by dusting or spraying foliage
with pesticide. For a list of susceptibility of certain woody ornamentals
to Japanese beetle damage see the Mississippi
State study.
For home use, carbaryl (Sevin), malathion, imidacloprid (Merit) are
good choices. Many of the newer lawn and garden multi-insect products are
also effective. Pyrethroid containing chemicals are slightly more persistant.
Spinosad and Neem based products give a little protection. Roses or shrubs
may also be protected by covering with light netting. Handpicking adults from
plants is an almost hourly battle. Homemade concoctions and blended beetle
cocktail repellants are mildly effective, and may need reapplication every
one or two days.
Japanese beetle traps may catch up to 75% of the beetles that approach them.
Traps may lower beetle populations from 30% (1 trap per acre) up to 39% (10
traps per acre) if placed throughout a neighborhood. The trapped beetles must
be emptied from the traps every one to two days to prevent them from rotting
and releasing ammonia which is repellant to other Japanese beetles. Traps are
commercially available. Homemade traps are also effective in catching beetles
if baited with phenylethyl proportionate plus eugenol lure available at garden
centers and hardware stores. The traps are much more effective in attracting
Japanese beetles than in trapping them. Consequently, traps should be placed
as far away from the plants to be protected as possible. If traps are used,
place far away from susceptible plants. Traps, alone, are not likely to give
satisfactory protection to plants being eaten by adult Japanese beetles and
pesticides may be required, anyway.
For commercial operations, imidacloprid, acephate, or pyrethroids are
effective. Follow label directions for rates and safe use. It may be necessary
to apply some of these pesticides more than once for complete protection during
the weeks of adult feeding.
Grub control
Commercial preparations of the Bacillus popilliae (milky spore disease)
offer some slight effect as a soil treatment. These spores infect and kill only Japanese
beetle grubs. The spores are released into the soil and infect new grubs as
they come in contact with the bacterial spores. Milky spore preparations can
be applied from July until the first hard freeze to areas of turf grass that
are mowed to 2 to 3 inches tall. These areas are preferred egg laying sites
for adults and here, during the warm months, grubs feed close to the soil surface.
Results of milky spore have been disappointing, however, and generally
do not justify the expenditure. Milky spore treatment also provides little
relief for the homeowner from the onslaught of foliage feeding by the highly
mobile adults which fly into the area. Japanese beetle grub populations rarely reach
economic threshold levels as turf pests in home lawns. A general threshold
is 10 grubs per square foot (fewer on commercial turf) before turf damage becomes
an issue. In addition, only small areas of the turf may be infested, so do
not assume the entire area is infested. Heterorhabditis species of nematodes
may be a viable non-chemical alternative for turf protection, but application
directions must be carefully followed.
Soil insecticides for grub control are available, but rarely needed or justified
for home owners. Imidiclporid-based insecticide applications any time from
late spring through summer are fairly effective. The residual life of the soil
applied chemicals varies, so follow the label instructions. Killing all grubs
in a lawn will not protect your shrubs from Japanese beetle adult feeding so grub
insecticides for adult beetle control are an unnecessary use of pesticide.
No matter which product or approach is selected, be sure to follow label directions.
Recommendations for insecticides approved for control of these insects in home
lawns can be found under the "White Grubs" listing in the Insect
Control in Home Lawns section of the NC Agricultural Chemicals Manual.
Recommendations for insecticides approved for use on sod farms, golf courses
or other commercial sites can be found in the Commercial
Turf Insect Control section of the NC Agricultural Chemicals Manual.
Useful References
Recommendations of specific chemicals are based upon information on the manufacturer's
label and performance in a limited number of trials. Because environmental
conditions and methods of application by growers may vary widely, performance
of the chemical will not always conform to the safety and pest control standards
indicated by experimental data.
Recommendations for the use of chemicals
are included in this publication as a convenience to the reader. The use
of brand names and any mention or listing of commercial products or services
in this publication does not imply endorsement by the North Carolina Cooperative
Extension Service nor discrimination against similar products or services
not mentioned. Individuals who use chemicals are responsible for ensuring
that the intended use complies with current regulations and conforms to
the product label. Be sure to obtain current information about usage and
examine a current product label before applying any chemical.
Other Resources
For assistance with a specific problem, contact your local North Carolina
Cooperative Extension Service.
Published by North Carolina Cooperative Extension Service
Distributed in furtherance of the Acts of Congress of May 8 and June 30,
1914. Employment and program opportunities are offered to all people regardless
of race, color, national origin, sex, age, or disability. North Carolina
State University at Raleigh, North Carolina A&T State University, U.S.
Department of Agriculture, and local governments cooperating.
© 2001 NC Cooperative Extension Service
Prepared by: James R. Baker & S. Bambara, Extension Entomologists
ENT/ort-44
July 1994 (Revised) April 2002
Web page last reviewed January, 2008 by the webperson.