Posted on Jun 27, 2014 by Michael Gray

Japanese Beetles and Silk Clipping: New Research on an Old Foe

On June 18, Robert Bellm, Commercial Agriculture Educator, observed Japanese beetles in Madison County, Illinois. Overall this season, I’ve received very few reports regarding this insect. With corn now rapidly growing into the late-whorl stage in many areas of the state, attention will soon begin to focus on protecting the pollination process from insect injury (silk clipping). Recently, some research was published concerning the effect that silk clipping by Japanese beetles had on the yield of corn. The research was conducted by researchers with the University of Tennessee and the University of Missouri from 2010 through 2012. The citation for their journal article is as follows:

Steckel, Sandy, S.D. Stewart, and K.V. Tindall. 2013. Effects of Japanese beetle (Coleoptera: Scarabaeidae) and silk clipping in field corn. Journal of Economic Entomology 106(5): 2048-2054. DOI:

During this multi-year study, the researchers manually clipped silks as well as caged Japanese beetles on ears. Hybrids used in their investigation included DeKalb DKC 64-83 VT Triple Pro (2010-11) and DKC 67-88 VT Triple Pro (2012). Key findings from this research are outlined below:

Summary Comments from Steckel et al. (2013)

In the coming weeks as the corn crop moves through the silking and pollination period, I encourage producers to scout their fields for this perennial insect pest and consider the economic threshold (referenced above) prior to making a treatment decision. Also, Japanese beetles tend to concentrate their numbers along field margins. Densities within field interiors may be far lower. These factors are important considerations before any rescue treatment is applied.

Mike Gray

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