Japanese Beetles Have Arrived

On Wednesday, June 16, we caught the first Japanese beetles of the year on the North Carolina State University campus in Raleigh. Last year Japanese beetles were not very abundant here so it will be interesting to see what this year brings. As most people know, Japanese beetles emerge once per year to feast on a variety of ornamental and crop plants. Their 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. It also means that one plant can be severely damaged while nearby plants are just nibbled on.

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 beetles grubs will not reduce defoliation of plants on that property since beetles fly in from great distances. Long-term protection for landscape and nursery plants can be achieved a neonicotinoid insecticide such as imidacloprid (e.g., Merit, Marathon II) or acetamiprid (Tri-Star). A new product with extremely low vertebrate toxicity but good efficacy for a number of pests including Japanese beetles is Acelepryn (chlorantraniliprole). For more information on the biology and management of adult Japanese beetles in nurseries and landscapes, consult Ornamentals and Turf Insect Information Note No. 147 at http://www.ces.ncsu.edu/depts/ent/notes/O&T/flowers/note147/note147.html.

From: Steve Frank, Extension Entomologist