Japanese Beetles are Eating My Elephant Ears

Beetle Identification

• Japanese beetles (Popillia japonica) have shiny, metallic-looking green or greenish-brown bodies. Their front wings look like polished copper. At nearly an inch long and 1/4 inch wide, Japanese beetles are highly visible in the garden. While other beetles have similar coloring, Japanese beetles have five tufts of white hairs under each wing cover and two patches at the tip of their abdomen. These alien invaders from Asia spend their youth as grubs buried deep in the soil, emerging as adults in early summer. Grubs are grayish-white, C-shaped, and have a "V" pattern in the tiny hairs on their hind ends. The adult beetles are voracious feeders, especially on hot days.

Damage

• Although Japanese beetles seem to prefer plants that grow in full sun, you may spot the insects feeding on elephant ears that receive full sun for only part of the day. The beetles prefer the juicy, green parts of the elephant ear leaves. As the beetles feed, avoiding the tougher veins, the elephant ear leaves become skeletonized. The beetles begin at the top of the plant and work their way downward. The insects release a pheromone that invites other Japanese beetles to feed on the plant.

Biological Controls

• Fill a pail or bucket with soapy water and pluck the beetles off the plant by hand. Drop them in the water to kill them. If the beetle population is low, this may solve your problem. A variety of traps are available, but the traps may attract more beetles than were present originally. To kill grubs, try bacterial milky spore disease, which targets only Japanese beetle grubs, but can take up to three years to reach peak efficacy. Parasitic nematodes kill younger, smaller grubs, and are available from many garden centers.

Chemical Controls

• Insecticides to kill Japanese beetle grubs include Imidacloprid and Halofenzide. Because of their armor, adult beetles are harder to kill. Try insecticides made with pyrethrum or Neem oil, which are not as toxic to benefcial insects. Stronger insecticides containing carbaryl or acephate may also be effective. Follow package directions on all pesticides for proper application and timing of repeat treatments.