Prepare for Japanese Beetles

From Steve Frank, Extension Entomologist

On June 11, I caught the first Japanese beetle of the year on the North Carolina State University campus in Raleigh. As most people know, Japanese beetles emerge once per year to feast on a variety of ornamental and crop plants. Favorite ornamental hosts include roses, rosaceous trees and shrubs such as crab apple, crape myrtle, and linden. Beetles aggregate on plants in response to plant volatiles (smells) and pheromones from other beetles. This aggregation can result in rapid defoliation of trees and shrubs. Japanese beetle traps do not offer any protection to landscape plants and may actually attract more beetles on to your property, so hang them in your neighbor’s yard. Likewise, treating a lawn for Japanese beetle grubs will not reduce defoliation of plants on that property since beetles fly in from great distances. Landscape and nursery plants can be protected with pyrethroid insecticides. For longer protection, use a neonicitinoid insecticide such as imidacloprid (e.g., Merit, Marathon II) or acetamiprid (Tri-Star). For more information on the biology and management of adult Japanese beetles, consult the insect note at http://www.ces.ncsu.edu/depts/ent/notes/O&T/flowers/note44/note44.html.