TO his delight, and somewhat to his surprise, Jeff Ball has all but eliminated Japanese beetles from his suburban garden, just south of Philadelphia - without using a single spray. What's more, he has accomplished this feat even while neighboring gardens - a little more than a hundred yards away - continue to be overrun by the voracious little invaders.
Mr. Ball, host of the National Gardening Association's videotape series and author of several gardening books, has kept his roses, raspberries, and lawn almost blemish free through the judicious and persistent use of pheremone traps.
Ball's delight and surprise stem from the fact that every gardener he knew who had ever used pheremone Japanese beetle traps had all said the same thing: ``Traps don't work.'' At least one university study says the same thing.
But he found differently.
Ball is not totally certain why the traps should work for him when neighboring yards are infested. But he suspects the key to success is ``to site them right in the first place and stick with the program over several years.''
Grubs of Japanese beetles eat the roots of lawn grass in their larval stage in fall, and again in spring. Then they pupate and emerge as hungry adults roughly four to six weeks after the last frost.
Some years back, Ball decided to try Japanese beetle traps in his yard. He sited the traps accurately: 50 feet from his garden, with the prevailing winds blowing the pheremone scent away from the raspberries he wanted to protect. Beetles attracted by the scent would come across the trap before they reached the raspberries.
That year, Ball collected five bags of the beetles, and about as many again the following year. He began to agree with the general assessment that traps may be good for monitoring, yet no good for lowering the count. But he persisted.
In the third year, the drop was dramatic - down to the equivalent of about one bag full. In the fourth year, his traps produced only a handful - the count has remained low the two seasons since.
At first, says Ball, ``I thought something had happened to collapse the beetle population in my area generally. But then I found that neighbors as close as 200 yards away were still inundated with them.''
Japanese beetles can fly considerably farther than 200 yards. But Ball theorizes that as long as there is food in the vicinity where they hatched, they don't bother.
He also believes that it took two years of trapping before the egg-laying population in the immediate vicinity of his home had been dented enough for the population to decline noticeably.
If you talk of Ball's experience with others in the lawn-care advice business, they express surprise. Most agree, however, that they have not heard of traps being used as consistently as they are used at the Ball residence.
Still, most of them suggest there is an easier way: One application of milky spoor (a pathogen of the Japanese beetle grub) on your lawns is generally all you will need.
Sheila Daar, an Integrated Pest Management specialist from Berkeley, Calif., notes that the beetles like to lay their eggs in relatively short grass. Raising the mowing height to 2 to 3 inches is a good idea.
Beetle eggs need constant moisture to remain viable, too. So widely spaced, deep waterings that keep the lawns healthy, yet allow the soil surface to dry out, can reduce pest numbers considerably.
Meanwhile Jeff Ball plans to continue with the traps. As long as they're effective, why change? he asks.