(page 5 of 15)
NAME: Japanese beetle (Popillia japonica)
DATE INTRODUCED: 1916
HOW IT GOT HERE: Arrived as a stowaway in iris bulbs shipped from Japan
First found some 90 years ago in a New Jersey nursery, these metallic-green insects with copper-colored wings are voracious eaters of ornamental trees and shrubs, as well as vegetable crops. “They love to eat roses,” says Summers. “But they also feed on 300 different types of plants.” Adult beetles, which are around a half-inch long, burrow inside foliage and chew on the leaf tissue between the veins, leaving leaf skeletons. Equally hungry larvae—inch-long milky-white grubs with brown heads—hide in wet, shady sections of grass, feeding on the roots.
THE FIGHT: Traps help detect the emergence of these garden pests but are not recommended for controlling their spread, since the pheromone bait attracts nearby beetles. Handpicking is effective for small populations, and chemical insecticides help control large populations, though sometimes at a risk to nonpests, such as honeybees.