Roanoke Times
Copyright (c) 1995, Landmark Communications, Inc.
DATE: THURSDAY, July 6, 1995 TAG: 9507060031
SECTION: CURRENT PAGE: NRV-9 EDITION: NEW RIVER VALLEY
SOURCE: LELIA MAYTON
DATELINE: LENGTH: Medium
They're back! I wasn't really surprised. They always appear on the false bamboo by my kitchen window during the last week of June. They are Japanese beetles!
Japanese beetles appear at the end of June and disappear by mid-August. But while they're around, they especially enjoy feasting on some of our favorite landscape plants and trees, such as roses and birch trees.
So how do you control them or get rid of Japanese beetles?
It helps to first understand the life cycle and habits of the Japanese beetle.
For 10 months of the year, the Japanese beetle exists as a grub beneath the soil. The C-shaped grub pupates in mid- to late May, emerging as an adult in early June to mid-July.
Adult beetles live approximately 11/2 months, are very active during the day and can fly great distances.
In July through early August, females lay the bulk of their eggs approximately three inches under the turf. One to four eggs are laid in batches daily until a total of 40 to 60 eggs has been deposited.
The tiny larvae hatch from their eggs in late summer to early fall and feed on small roots and organic material in the soil.
Larvae develop very quickly and grow to up to one inch before winter. As soil temperatures get colder, larvae burrow deeper into the soil, overwintering about six inches beneath the surface. In the spring, when soil temperatures go above 50 degrees, they return to the upper two inches and resume feeding.
Birds prey on Japanese beetle grubs, but they don't particularly like to eat the adult beetles. Flocks of birds on a lawn can indicate the presence of Japanese beetle grubs. Although birds eat large quantities of grubs, they are not a reliable means of control, and they make holes in the turf.
Some birds such as crows pull up small pieces of the turf and scatter them over the lawn.
Several small mammals, including moles, shrews, and skunks, also eat the grubs. Skunks are the most diligent animal predators. Skunks make holes in the turf, but scarcely larger than those made by the birds and usually not conspicuous enough to disfigure the turf. Most homeowners are concerned about other problems with skunks!
Milky spore disease is the most popular and effective biological control measure used against the Japanese beetle. The bacterial fungal spores infect and kill the larvae which, in turn, release more spores to control other grubs. This disease, which is completely harmless to humans, is not an immediate form of control. It takes two or three years to get good control this way. Also, it is more effective if everyone in a neighborhood uses it. However, spores can and do spread naturally from treated to untreated areas.
Traps with pheromone lures are popular for catching adult beetles. The major mistake people make is placing the traps below or adjacent to plants they want to protect, thus simply attracting more beetles to the area.
Instead, place traps away from plants you want to protect, if possible 20 to 30 feet away.
One of the easiest ways to remove beetles from plants is to shake the plants in the early morning when the temperatures are lower and the beetles are sluggish. Kill the beetles by shaking them into a pail containing water and either dish detergent or kerosene.
The Japanese beetle is a gregarious insect; accumulations on a plant attract other beetles flying in the area. Researchers have found that a plant kept nearly free of beetles attracts only about half as many beetles as a plant where beetles are allowed to accumulate.
Lelia Mayton is a family and consumer sciences agent with the Virginia Cooperative Extension Service at the Montgomery County Extension office in Christiansburg. If you have questions, call her at 382-5790.
by CNB