Montana State University

New guide available on Japanese beetles in Montana

June 20, 2014 -- MSU News Service

Japanese beetle adults feed on a rose. (Photo by Whitney Cranshaw, Colorado State University, Bugwood). This is a Japanese beetle larva. (Photo by David Cappaert, Michigan State University, Bugwood.org).

Japanese beetle adults feed on a rose. (Photo by Whitney Cranshaw, Colorado State University, Bugwood).    High-Res Available

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MSU News Service
Tel: (406) 994-4571
msunews@montana.edu

BOZEMAN – A guide to help Montanans detect, monitor and control Japanese beetles is now available from Montana State University Extension.

Prior to 2013, the Japanese beetle was established in a small area of Billings, but had not spread. In 2013, it was introduced into seven municipalities through shipments of infested nursery stock, said  insect diagnostician Laurie Kerzicnik.

The larvae are pests of turf grass. Lawns with yellow patches might indicate an infestation. The adults feed on more than 300 plants, but they prefer roses, apple, grape, cherry, raspberry and linden.  They also eat field crops, vegetables and ornamental bushes.

Japanese beetle larvae, also known as grubs, are about one inch long when they mature. They are off-white, have a C-shaped body and three pairs of legs.

Japanese beetle adults can be half an inch long. They have a metallic green, oval body with bronzed outer wings. They have five small tufts of white hair along the sides of their abdomen and two more patches protruding from the last segment of their abdomen.

A variety of approaches are available to control Japanese beetles, Kerzicnik said. Montanans can use insecticides or plant resistant species, such as lilacs, spruce and the common chokecherry. They can use biological controls, which include parasites, nematodes, fungi or other organisms.

For more information about the Japanese beetle, including its life cycle, behavior, susceptible plants, and control methods, Montanans can request an MSU Extension MontGuide by visiting the online store or emailing orderpubs@montana.edu. The MontGuide was written by Kerzicnik and MSU Extension Horticulture Associate Specialist Toby Day. It is a June 14 publication numbered MT201404AG.

Evelyn Boswell, (406) 994-5135 or evelynb@montana.edu