The Purdue Plant and Pest Diagnostic Laboratory

What's Hot at the P&PDL
June 4, 2012

Japanese beetle monitoring traps confirm early season in 2012

Timothy Gibb and Doug Richmond, Purdue Turfgrass Entomologists, Department of Entomology

As anticipated, Japanese beetles are out early this year.  The first beetles were captured in central Indiana during the week of May 14-18. (This is nearly a month earlier than most years.)  We expect Japanese beetles to arrive in full force in this area within the next 2-3 weeks. 

Because we have never experienced such an early spring, it is difficult to predict just how the beetle populations will respond.  We know that the beetles are active early but we do not know if this means that they will be with us longer into the summer or not.  Also, keep in mind that dry conditions do not favor beetle emergence but a significant rainfall event could potentially shift emergence into overdrive.

It is safe to say that we need to prepare now, however.

Protect susceptible plants, especially those that have been recently transplanted or those that are stressed for one reason or another. Favorites host plants for Japanese beetles include linden, crab apple, plum, and other fruit trees, rose bushes, grapes, and several garden variety vegetables. 

Grub preventative applications probably cannot be applied too early this year. The newer long lasting grub control products will be a great advantage this year because we do not know exactly how long the grubs will be feeding on the turfgrass.

If dry weather continues, oviposition and grub feeding may be concentrated in irrigated turfgrass.

With all insecticides, either for adults or for grubs, it is critical to follow the label directions exactly when making applications. 

Click image to enlarge

Japanese beetle on leaf

Purdue Plant & Pest Diagnostic Lab Purdue Cooperative Extension Service