Japanese Beetle - How to Control Japanese Beetles.
IN THE GARDEN: CONTROLLING JAPANESE BEETLES!!! From friend and colleague,
Ron Wilson
Controlling Japanese Beetles (Adults)
What do Japanese beetles look like? - Adult Japanese beetles
are metallic green color, oval, and about 3/8 to ½ an inch long,
and about ¼ inch wide. The wing covers are copper brown, and their
abdomen has a row of five tufts of white hairs on each side.
Where do Japanese beetles come from and what will they do?
- Japanese beetles are the adult stage of grubs in the soil (one of many
types of grubs). They emerge from the ground and begin to feed on plants
sometime in late June and early July. They feed on over 400 species of leafy
plants, eating leaves, flowers, and sometimes the fruit. They are most active
during the warmer parts of the day and especially active on warm, clear,
sunny days. Activity usually lasts about 4-6 weeks, after which the beetles
gradually die off. (Individual beetles live about 30-45 days.) After mating,
females lay their eggs in the turf, which hatch into grubs, and feed on
turf roots in the soil until cold weather drives them deeper into the soil.
They move back to the top when temperatures warm (spring), and emerge as
adults the following June.
One beetle does little damage, but they usually feed in groups, starting
at the top of a plant and working down, and group feeding can cause severe
damage. Early arrivals release a hormone, which attracts other adults to
the plants. Females also release an additional sex pheromone to attract
males. Odors released from beetle-damaged leaves also assists in attracting
beetles to a particular plant. And, although Japanese beetle damage looks
devastating, their feeding rarely kills plants. Note: Although adult beetles
typically only make short flights as they move about to feed or lay eggs,
they are extremely mobile and have been known to fly as far as 5 miles.
How do I control Japanese beetles? - Cultural Controls:
Don't plant trees and shrubs that Japanese beetles like. Japanese and Norway
maples, birch, pin oak, rose of Sharon, sycamore, ornamental apples, plums
and cherries, roses, willows, lindens, hollyhock, sassafras, grapes, filbert,
even poison ivy are a few of their favorite plants. If you do, just be prepared
for 'possible' Japanese beetles.
Physical Removal: Removing them by hand, keeping lower populations, and not allowing beetles to accumulate (beetles attract beetles) will help. Hand picking, hosing them off (especially early on), or shaking them off the plant (in a bucket of soapy water) early in the morning when the insects are sluggish works great. Highly valued plants could be covered with cheesecloth, grow covers, or fine netting during the peek of beetle activity.
Chemical Controls: Many insecticides are labeled for
use against Japanese beetle adults. If you do take this route,
1.) Thoroughly treat foliage and flowers
2.) Use spreader sticker to increase duration of effectiveness
3.) Repeated sprayings may be needed (check labels)
4.) Do not spray when bees are active
5.) Insecticidal soaps will kill adults hit by the spray, but provide no
residual protection
6.) If spraying edibles, check labels for any restrictions. Insecticides
for adult beetles include Eight, Sevin, Orthene, Rotenone / Pyrethrum sprays,
Insecticidal Soaps, Neem Oil, and Merit (if applied to plants 3 weeks in
advance, and it will need assistance with other foliar sprays in heavy populations).
Natural Control: Birds such as grackles, cardinals and larger birds will feed on the adult beetles. Mechanical Control -Trapping: There are several types of Japanese beetle traps, with both a floral / food lure and a sex pheromone lure, and can draw in thousands of beetles each day. Research has shown these traps actually attract more beetles than are caught. Susceptible plants may be along the flight path of the beetles, and could suffer more than if no traps had been used at all. If using traps, place them well away from gardens and landscape plants - maybe in the neighbor's yard!
Note: Because beetles are attracted to favorable plants
from a considerable distance, controlling grubs in the lawn will not protect
landscape plants from adult feeding.
[Resources include OSU Extension / UK Extension Service]
About Ron: Ron Wilson hosts “In the Garden” on WKRC from Cincinnati Ohio and XM Channel 165 from 6-9a.m. Saturday mornings. He has a degree from The Ohio State University in Landscape Horticulture. He’s also the Marketing Manager for Natorp’s Garden Stores, Landscape Nursery. And, a Personal Yardboy!
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