Japanese Beetles

Description:
Anyone who has crape myrtles or roses in the Nashville area has more than likely fought many a war against Japanese beetles. They are 1/2" long beetles with copper colored wings and the adults have a metallic green sheen and they can destroy the blossoms of roses and crape myrtles right before your eyes. They emerge from the ground in June and wreck havoc all summer. Before that Japanese beetles are below ground in their larval stage and feed on the roots of turf primarily, but will feed on garden plant roots as well.

Damage:
Japanese beetles skeletonize leaves and devour flowers of more than 275 kinds of trees, shrubs, turf, field crops, and garden plants (especially roses, crape myrtles, and hollyhocks.) The grubs feed on the roots of grasses and garden plants. The damage grubs cause in lawns is distinctive. It starts as localized brown, dead patches of lawn and spreads as the grubs travel and feed.

Prevention:
Prevent the introduction of Japanese beetle grubs in your yard by inspecting the plants you install and treat all new sod with parasitic nematodes. This will prevent grub damage but will not effectively reduce the adult population unless your entire neighborhood took the same precautions.

Management:
Mild Infestations: Grubs are susceptible to a disease called milky spore. This disease has been packaged and can be applied to the lawn, infecting the grubs, without harming beneficial insects. It takes a while for the milk spore to take hold, but it does prevent the grubs from developing into adults.

When adults are present in small numbers, hand pick them from plants and drown them in a bucket of soapy water. (The soap prevents them from flying.) Azadirachtin (Neem), when sprayed on the foliage of roses, seems to deter Japanese beetles, but there is no guarantee.

Severe Infestations: When worse comes to worse hit grubs with diazinon or imidacloprid (Merit, GrubEx).

Adult beetles can be sprayed with pesticides such as Imidan, Neem, Sevin, or Orthene. Always follow label application instructions.