Japanese beetle adults have a half-inch to three-fourths-inch
long body with copper-colored wing covers and a shiny, metallic
green head. A key characteristic is prominent white tufts of
hair along their sides. They also have an overwhelming appetite
for your favorite rose. Adults feed in herds on many deciduous
trees, shrubs and vines, such as linden, Japanese maple,
sycamore, birch, elm and grape. They generally do not feed on
dogwood, forsythia, holly and lilac. Japanese beetle adults feed
on flowers and fruits and skeletonize leaves by eating the leaf
tissue between the veins. Feeding is normally in the upper
portions of trees. Beetles prefer plants in direct sun, so
heavily wooded areas are rarely attacked.
Adults can be with
us until mid-August. The life cycle is similar to a June bug,
only it runs a few weeks later. After mating, females lay eggs
in turf. The eggs hatch into grubs in August. Grubs feed on
plant roots until cold weather drives them deeper into the soil.
Adults emerge in summer of the following year.
The bacterial control, milky spore sold as Doom or Grub
Attack, is frequently recommended to control Japanese beetle
grubs. In our area, milky spore is generally not recommended,
since it controls only Japanese beetle grubs. Also Japanese
beetle grubs must already be infesting the turf for milky spore
to work effectively. Pesticides commonly used for lawn grub
control will also control Japanese beetle grubs.
Controlling Japanese beetle grubs does not significantly
reduce the number of adult beetles the following year. The
beetles are good fliers and easily travel a couple miles in a
single flight. Evidence suggests that adult beetles are
attracted to previously damaged leaves. Therefore, reducing
feeding damage now can result in less feeding damage in the
Generally, pesticide sprays of cabaryl sold as Sevin can
reduce damage for up to two weeks, but four to seven days is
more likely. Sevin is toxic to bees. Synthetic pyrethroids can
also be effective, but they tend to break down quickly with
extreme heat. These would include permethrin and bifenthrin. The
Japanese beetle repellent made from Neem has not been shown to
Picking beetles off by hand every couple of days may be just
as effective as spraying. When disturbed, the beetles fold their
legs and drop to the ground.
Covering plants with floating row covers can protect prized
roses and ripening fruit.
Japanese beetle traps are not recommended since they can
actually increase damage by attracting more than they kill.
A number of birds, such as grackles, cardinals and
meadowlarks, feed on adult beetles. Two native predator insects
and a couple of introduced parasites may also help to keep
Japanese beetle populations in check. Protect natural enemies by
keeping the use of conventional pesticides to a minimum.
Although damage looks devastating, Japanese beetle feeding
rarely kills plants. Therefore, confine control of beetles to
shrubs and small trees near main building entrances and other
important landscape locations where damage is obvious.
Protecting a prize rosebush or a newly transplanted linden tree
is a good idea.
If you haven't sown pumpkins for fall decoration, the correct
timing is usually around Father's Day. Vining pumpkins need at
least 50-100 square feet per hill, with the larger pumpkins
requiring the larger area. Hills should be five to six feet
apart and rows of hills should be 10-15 feet apart. Each hill
should have about four seeds per hill, planted about an inch
deep. The miniature varieties such as the Jack-Be-Little are
sometimes grown in rows with seeds planted every eight to 12
inches, then thinned to about two feet apart in the rows.
Fall decoration pumpkins should be cut after the color is
acceptable but before the vine dries, in order to have a good
stem attached to the pumpkin.
University of Illinois Extension]