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Understanding The Japanese Beetle And Their Control

24 Dec , 2015  

Most gardeners tend to relax and enjoy the fruits of their labor, as well as the beauty of what they have created. But wait, why do leaves of the linden trees seem to have a tattered appearance? What is that insidious cluster on the rose blossoms? Upon a closer look, you realized that you have the company of the Japanese beetles.

What are the Japanese beetles?

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They are destructive insects that measure around 3/8 inches in length and which are metallic-green in color. They mostly appear from the ground in late June and feed in groups, starting at the tops of your plants working their way downwards. On their own, Japanese beetles do not consume much. However, in a group, their damage is normally devastating, if not heartbreaking. These insects feed on more than three hundred varieties of plants ranging from shrubs to full grown trees. They are particularly fond of plants that grow rapidly in direct sunlight. These include a majority of landscaping plants. Worst of all, their larvae live on the soil for number of months and wreak havoc on the roots of irrigated vegetations and turf grass.

Where did the Japanese beetle come from?

The first sighting of Japanese Beetles in this country was in 1916, most likely arriving in the soil of imported nursery vegetation stock. Unfortunately, they have steadily moved outwards at a rate of around 50 miles a year. While most states have put in place rigorous controls on the acceptance of out-of-state nursery stocks, these pests have still been able to infest all portions of the country.

Unfortunately, the damage caused by these pests is particularly bad at the outer reaches of their territory, and for a good reason. There are very few natural controls that exist in the newly colonized locations. Japanese beetles spend their first 10 months of their lives hidden in the soil as grubs, mostly starting from August and September. While in this state, they also cause a lot of damages on the roots.

Natural enemies

While quite a number of birds eat Japanese beetles, they mostly prefer feeding on the grubs. Unfortunately, in their effort to search for these grubs, birds tend to tear up pieces of your turf. This is a small problem compared to lawn damages caused by skunks and moles when trying to search for grubs to feed on. Insects such as the praying mantis also occasionally feed on grubs and adult beetles, and so do a few native flies and wasps. Nevertheless, the role they play in controlling this pest is relatively minor.

Natural control

The Japanese beetles are not considered a major pest in places such as their native Japan and Korea. The main reason for this is that there are a few natural controls in place. These include:

• A bacterial disease referred to as milky spore, that infects and kills the grubs

• Microscopic worm that gobbles the grubs

• An intestinal parasite commonly referred to as gregarine which attacks the grubs

All these controls were introduced in the U.S. several years ago and have kept the beetle in check. Unfortunately, on small-scale basis, natural control hasn’t been very effective because adult beetles are able to easily fly into and out of the treated areas. Moreover, natural controls are effective only on grubs and not adults beetles.

Chemical control

It is quite hard to control adult Japanese beetles with chemical sprays. Furthermore, these products also eradicate beneficial insects such as bees. Rose fertilizers with systematic insecticides also have no effect because individual beetles actually consume very little. Simply irrigate and fertilizer your vegetation to prevent grubs from damaging your lawn.

All in all, when it comes to controlling Japanese beetles, you actually have a number of options, each of them offering differing degrees of effectiveness. In good gardens, pests are controlled either naturally or chemically. These two approaches are effective, simple and safe. Simply put, defeat your enemy before he actually defeats you!

If you need pest control products for your garden at home, visit one of the reputable Queens garden centers and let the experts there guide you further.