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February 26, 2012

Destructive Insects - Control of the Japanese Beetle

-by Debra Anchors

As of November 2011, The USDA Animal and Plant Health Inspection Service has identified the Japanese Beetle as the #2  most destructive insect in the USA.

The adult Japanese Beetle feeds on the foliage and fruits of several hundred species of plant life and leaves behind skeletonized leaves and large, irregular holes in leaves. The grubs develop in the soil, feeding on the roots of various plants and grasses and often destroys turf in lawns, parks, golf courses, and pastures. Today, the Japanese beetle is the most widespread turf-grass pest in the United States. Efforts to control the larval and adult stages are estimated to cost more than $460 million a year. Losses attributable to the larval stage alone have been estimated at $234 million per year—$78 million for control costs and an additional $156 million for replacement of damaged turf.

In its native Japan, where the Beetle’s natural enemies keep its populations in check, the Japanese Beetle is not a serious plant pest.  But, in the United States, the Beetle entered without its natural enemies and found a favorable climate and an abundant food supply. By 1972, Beetle infestations had been reported in 22 States east of the Mississippi River and also in Arkansas, Iowa, and Missouri. Since then, the pest has spread to Southern and Western States, but tough regulations and careful monitoring have prevented its establishment there. Without its natural checks and balances, the Japanese beetle has become a serious plant pest and a threat to American agriculture.

Life stages of the Japanese Beetle
© Joel Floyd 

Several traps using a floral lure and sex attractant are available, but these traps are ineffective and not recommended for general use unless special conditions are met. The traps have been demonstrated to be effective in reducing damage and populations only when landscapes are isolated from other Japanese beetle breeding areas or when mass trapping (involving everyone in the neighborhood) is used. In most urban areas, traps tend to attract more beetles into the area than would normally be present. In this situation, adult feeding and resultant grub populations are not reduced.

Beetle grubs are best controlled when they are small and actively feeding near the soil surface, usually late July to mid-August. However, with the development of new grub control chemistry (e.g., imidacloprid and halofenozide applications in June and July have sufficient residual activity to kill the new grub populations as they come to the soil surface in late July through August. Control of grubs in late fall or early spring is difficult, because the grubs are large and may not be feeding. Only trichlorfon and carbaryl formulations are available for such rescue treatments. The key to good control is to make an even application and water thoroughly.

Life Cycle of the Japanese Beetle

Gardeners joyfully toil in their gardens to enjoy the beauty of their flowers; Japanese Beetles will deny the gardener their reward. The most effective product I have found to control Japanese Beetle infestations is Optrol from Plant Care Science.  Optrol contains the highest amount of imidacloprid approved for sale on the market and is by far the most effective defense I have found.  Optrol is a new product and not widely available at your local retailer. If readers are having a challenge finding Optrol, please leave a comment and I’ll try to find a source for you.

Sources referenced while writing this article:
Ohio State University
United States Department of Agriculture

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  1. I had Japanese Beetles last year for the first time. What a nuisance! I am still learning about this new enemy and had no idea that they overwintered in the ground. I am dreading their reappearance this summer!

  2. Very informative post. Now we can effectively identify and get rid of this pest.

  3. They have been quite a pest for my garden, but I think I have them somewhat under control after several years. I use the Milky Spore and the traps. Last year, I did not need to use the traps because there were not that many of them. It all must be working. They do nibble on my green bean plants, so I need to do something in the veggie garden. Great post!

  4. My new property is infested with Japanese beetles and every shovelful of dirt has a handful of grubs. This year I will be spraying everywhere with Nemetodes. I have used this natural rememdy in 2 other locations with great success.

    1. Thank you very much for posting your experience. Do you have a large population of moles as well? Those grubs are one of their favorite meals.

  5. It’s a classic great for me to go to this blog site, it offers helpful suggestions


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