Japanese Beetle Wreaking Havoc

Japanese beetles have returned with a vengeance to Wisconsin. It's ''the bug from hell,'' as University of Wisconsin-Madison entomologist Phil Pellitteri calls it. They attack a wide variety of plants - roses are a favorite - leaving a trail of destruction that includes leaves so full of holes they resemble lace.

''We really don't have any other kind of insect that has this kind of impact as far as making gardening no fun,'' Pellitteri said.

Wauwatosa was hit in July, while Brookfield is just now encountering the pests, said Debbie Pings, a horticulturalist at Hawks Nursery. Across the region, neighborhoods may seem fine one day and be overrun a few days later. How can you tell they've arrived? Look for browned birch or linden trees.

The Japanese beetle is about a half-inch long, with a vivid green body covered by wings that look almost bronze. They hit lawns, gardens and trees every July - give or take a few weeks - and at the end of their season, lay their eggs in lawns. The larvae grow, eat and sleep underground until the following summer.

Sprays and traps

Defending against the beetles is not easy. The most common method is to spray with chemicals. Horticulturalist and gardening expert Melinda Myers suggests landscape contractors who are just beginning to see the beetles try an organic insecticide made of neem. She says it is most effective when used early.

If neem does not work, there are many synthetic sprays that may be effective, but they carry more risks.

Sprays marked for use against Japanese beetles containing the active ingredient imidacloprid. The insecticide is sold under many brand names and for many different purposes, including as a flea killer for pets. She cautioned against using sprays on the rose blooms themselves. ''You don't want to spray the flowers because you kill the bees,'' she said. Bees are needed to pollinate the plants.

Another problem with sprays is that they must be reapplied at least once every three days, Pellitteri said.

Beetle traps may actually do more harm than good. Myers, Pellitteri and Pings agreed that beetle traps, which work by attracting the beetles into a plastic bag with a tapered neck, may actually attract more beetles into your garden in general.

''They get thousands in the trap, but I'm not sure they have thousands in the tree,'' Myers said.