False Japanese Beetle (Strigoderma arbicola) Showing up in Iowa

June 25, 2015

Here is a post from Dr. Donald Lewis, entomologist at Iowa State University.  In recent weeks, we have both been contacted about Japanes beetles (Popillia japonica) showing up in central Iowa.  Don has found that these are actually False Japanese beetles (Strigoderma arbicola). We do get Japanese beetles here, although last year populations were low.

Here is Don's post.

From: Lewis, Donald R [ENT]

Pest identification is a keystone to IPM.  An example going on now is the emergence of False Japanese Beetles (FJB) in eastern and central Iowa.  As the name implies, false Japanese beetle (Strigoderma arbicola) is very similar in appearance to the true Japanese beetle.  The major difference is the coloration.  False Japanese beetles do not have the bright green and copper coloration of the Japanese beetle.  They are dark tan to brown though the thorax may appear metallic green on some specimens.  False Japanese beetles do not have the five white hair tufts that are prominent on each side of the abdomen of the Japanese beetle.   Here is a link to a close-up photo of FJB where these characteristics can be viewed. 


The BugGuide website uses the common name “sand chafer” which matches very well the locations where we must commonly see this beetle in fields, gardens and lawns.  However, the common name “false Japanese beetle” has been used in Iowa for at least the past 50 years!  The False Japanese Beetle is moderately common in the state but varies greatly from year to year.  Others are reporting more than usual this year.

Technical information about false Japanese beetle:  http://bugguide.net/node/view/44690

An old article about FJB:  http://www.ipm.iastate.edu/ipm/hortnews/1999/7-2-1999/fjapbeet.html  Note since 1999 the true Japanese beetle has expanded its range in Iowa to 63 counties (not the 5 listed in the chart).


Donald Lewis

Donald R. Lewis


Department of Entomology

Iowa State University

Ames IA 50011