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 The adult beetle is about one-half inch long, says
Ken Johnson, University of Illinois Extension horticulture educator.
Along with the copper-colored wing covers and metallic heads, the
beetles have prominent white tufts of hair along their sides. Adults
feed on over 300 different species of plants and the larva, c-shaped
white grubs, feed on turf roots.
Some of their favorite plants include linden, rose, crabapple,
willow, grape, and raspberry, Johnson says. Adults will begin
feeding on the upper, sunlit portions of plants and work their way
down. Their feeding damage can cause leaves to look lice lace. When
feeding is heavy, entire branches can be stripped of leaves.
"One of the reasons they are so destructive is that they are
attracted to plants that have already been damaged," Johnson says.
"Since large numbers of beetles can be attracted to susceptible
plants, it is recommended to take action as soon as the first
beetles are seen.
Johnson offers several interventions to manage Japanese beetles.
Adults can be removed by hand. The best time to do this is in the
early morning while they are still sluggish. Put a few inches of
water in a container along with a drop or two of soap to break the
surface tension of the water and allow the beetles to drop into the
water.
High-value plants, such as roses, can be covered with cheesecloth or
other fine netting during peak beetle activity to protect them.
"Just make sure that the openings are small enough to keep the
beetles out," Johnson says. [to top of second
column] |
Japanese beetle traps are not recommended for managing
populations of beetles. "The traps attract far more beetles than they can trap
and may end up doing more damage than good," Johnson says.
Chemicals can also be used to help manage beetle populations.
Check with your local Extension office for the most up to date recommendations.
Some chemicals will require multiple applications. "When choosing a product,
make sure that the site/plant that you plan on applying it to is listed on the
label," Johnson says. "Always make sure to read and follow all label
directions."
Controlling Japanese beetle grubs in your lawn won't have a significant impact
on adult populations. The adults are capable of flying long distances and will
fly in from adjacent properties. If you don't want to fight the beetles you can
try growing plants that are unattractive to them, such as columbine, begonia,
dogwood, forsythia, holly, impatiens, lilacs, hosta, and violets.
People are often concerned about smashing Japanese beetles, believing the
beetles release pheromones in the process that may attract more beetles. Johnson
says that while virgin females do produce pheromones to attract males, once they
mate, they no longer produce pheromones.
More information on Japanese Beetles is available through the Living with
Japanese Beetles webinar available on University of Illinois Extension
Horticulture YouTube channel.
[SOURCE: Ken Johnson, Horticulture
Educator, University of Illinois Extension] |
