Japanese Beetle
What is the Japanese Beetle?
The Japanese Beetle (Popillia japonica) is an invasive insect that can cause some pretty nasty damage to your favorite ornamental trees and shrubs. It eats the tender tissues between the veins of the leaves of plants that it attacks and all that's left of the leaves are the brown, skeletal remains.
How did the Japanese Beetle get to the United States?
The Japanese beetle is native to Japan. The insect was first discovered in the United States in 1916 near Riverton, New Jersey in a nursery. It is thought that beetle larvae got into the United States in a shipment of iris bulbs before inspections of imported goods entering the country began in 1912.
What kind of plants to they eat?
Japanese Beetles are attracted to sweet smells and enjoy rose bushes, linden trees, grape vines, canna, and crape myrtle.
How can we control them?
There are many ways to control the Japanese Beetle population around your yard such as:
- Hand pick and dispose of the first beetles you see usually in late June and July. These first beetles sent out pheromones that attract more beetles to the area.
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Plant non-attractive plants such as arborvitae, baby’s breath, begonia, bleeding heart, buttercups, columbine, catnip, chives, garlic, tansy, daisies and flowering dogwood around your yard to keep the beetles at bay.
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Japanese Beetle traps attract the beetles with flowery scents and pheromones. Some studies have shown a trap may actually increase the number of beetles in your area and could possibly increase the damage.
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There are also insecticides you can purchase at you local garden center to kill the adult beetles.
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During the early spring and into early June, you can use a product containing a bacterium called Milky Spore (Paenibacillus popilliae) which attacks the Japanese Beetle in its larval stage. This can take up to five years to be an effective control.
- Spreading the remains of dead beetles in areas you want to protect can help keep them at bay, also.
Will my trees and plants survive being eaten by the Japanese Beetles?
Japanese Beetles can cause significant stress to trees and plants. Depending upon many other factors, the trees and plants may begin the process of decline.
What part of the state are Japanese Beetles, and where are they spreading?
Since 1994, 37 counties have reported seeing Japanese Beetles. These counties are mostly in eastern and central areas of the state moving towards the west.
Where can I find more information?
Iowa State University Department of Entomology is a great resource for more information.