Beetle mania Yeah, yeah, yeah, Japanese beetles are here.

July 15, 1991|By Frank D. Roylance | Frank D. Roylance,Evening Sun Staff

Suddenly they're everywhere.

Hungry Japanese beetles are on the roses, on the ornamental plants, grapes, berries and fruit trees, in the vegetable garden.

Entomologists say favorable weather conditions have made this a bountiful year for the half-inch long, brown and metallic-green bugs. Garden stores in some areas are doing a land-office business in beetle traps.

"We sell out of every one we can get our hands on," said John Warnken, assistant manager of Frank's Nursery and Crafts store in Owings Mills. "We could probably quadruple sales if we could get ahold of them."

Lee Hellman, a professor of entomology at the University of Maryland and an expert on the pest, said this year's Japanese beetle population "seems like more of a problem" compared with the last five or six years. "But it's nowhere near what the old-timers remember."

Before a barrage of bacterial assaults on the bugs after World War II, beetle traps would collect Japanese beetles by the gallons.

But that may bring little solace to today's homeowners.

Japanese beetles aren't fussy. They'll eat the foliage of nearly 300 species of plants in Maryland. And, as if that weren't %J enough, the adult beetles will soon be laying eggs beneath the grass. If there are enough of them, their growing grubs can kill the grass in August as they feed on the turf roots.

"The beetles will be around another two or three weeks in the numbers we have now, then they will start to decline," Hellman said.

But what to do now?

Maybe nothing, said Hellman. It depends on how heavily infested your lawn and garden are. If it's really bad, there are chemical and biological remedies.

And, while a lot of people are buying the beetle traps, baited with floral and sex lures, "we don't recommend them," Hellman says.

"Research shows that when you set a trap out, you can expect 10 percent to 40 percent more beetles flying in . . . than if you didn't have any trap at all," he said. "My suggestion is that you buy four traps and give one to each neighbor. It sucks all the beetles over to your neighbor's yard."

The bugs can also be picked or shaken from the foliage they are devouring, and tossed into soapy water, which kills them.

Beetle damage can be severe, if there are enough of them.

A few people with plum trees and grape vines in Montgomery and Prince George's counties have reported the beetles "have eaten all the leaves and plums down to the pit. That's a circumstance we haven't seen here since the 1930s," Hellman said. "In those circumstances, we recommend insecticides for control."

Unfortunately, there are no effective biological controls for adult beetles. But in general, he said, "most plants and shrubs can tolerate 10 percent to 30 percent defoliation. And the plant will recover, particularly if you support it with water and don't let it get too badly stressed."

As did the "killer" bee, the fire ant and the gypsy moth, the Japanese beetle, or Popillia japonica, got loose in this hemisphere by accident.

The beetles were probably first imported from Japan, as grubs, in the soil of potted plants before import controls took effect in 1912. They were first noticed in New Jersey in 1916.

Since then they have spread all along the East Coast and upper Midwest. They don't fly far on their own, but they have hitched rides in plant stock, camper trailers and aircraft as far afield as California.

During two or three weeks in July and early August, adult females lay 70 to 80 eggs in lawn grasses, primarily bluegrass. They like open, sunlit areas, but the eggs need several days of moist soil conditions to "plump up" if they are to survive.

We may owe this year's bumper beetle crop to rains at the proper time last July and August, plus a mild winter, Hellman said.

FTC If the eggs don't dry up, and aren't eaten by ants or predacious beetles, the larvae emerge by late August and go to dinner on the roots of the turf.

Japanese beetle grubs "are the major turf problem we have" in Maryland, said Hellman, who specializes in turf pests.

Grub-infested lawns and turf farms turn brown and die, and "you can pick up the turf as you would pick a rug from the floor," he said.

The grubs burrow deep into the soil for the winter, and reawaken in spring for breakfast. But damage is slight in spring, and "we recommend you don't treat them," Hellman said.

From mid-May to early June, the grubs change into pupae for two weeks, then emerge from the soil as adult beetles.

This year, Hellman said, the dry weather hardened the soil and delayed their normally staggered emergence. When rains finally came in the past few weeks, "you get this mass emergence," and suddenly, "they appear everywhere."

To tell whether you have a beetle grub problem, count them in late July or the first week in August. The white grubs lie in the

top 1 1/2 inches of topsoil. They're C-shaped, with a brown head and six legs. The skin between their legs is translucent, revealing the dark dirt in their gut.

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