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Angie Peltier

Angie Peltier
Former Extension Educator, Commercial Agriculture

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Hill and Furrow

Current topics about crop production in Western Illinois, including field crops research at the NWIARDC in Monmouth.
Figure. Japanese beetle; notice the iridescent metallic green head, the copper colored wings and the white tufts of hair along the sides and posterior. The tufts of hair or setae help in distinguishing the Japanese beetle from look alikes.
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Will the cold weather decrease Japanese beetle survival?

Japanese beetles were a topic of conversation throughout West-Central Illinois last summer for many people: homeowners concerned about their ornamental plants, farmers and home gardeners concerned about their fruits and vegetables and row crops farmers concerned about their corn and soybeans. I can recall traveling down certain stretches of highway with beetles continuously bouncing off of my windshield.

When dealing with very cold and snowy weather, one tends to grasp for potential positives. I believe that it is in this spirit that I have been asked several times recently about how the cold temperatures might affect Japanese beetle survival.

Unfortunately, according to Dr. Rick Weinzierl, University of Illinois Entomology Extension Specialist, Japanese beetles are very adept at surviving cold winter weather.

Beetles prefer to lay their eggs into soil that is covered by vegetation, such as grass. Eggs hatch after 10 to 14 days and larvae feed on live roots and decaying plant matter. Larvae go through several molts, eventually overwintering as 1 inch long "C"-shaped larvae.

Larvae are mobile in the soil and tend to crawl deeper into the soil profile as soil temperatures fall. Similar to a thick snow cover, a living ground cover such as sod has a moderating effect on soil temperatures when compared to bare soil (Figure). Overwintering insects also tend to shed excess water and produce more sugars in their cells that can act as natural antifreeze.

As Dr. Weinzierl notes, all of these survival strategies help Japanese beetles survive well in states that, unlike Illinois, are very cold every winter - like Minnesota. Illinois Japanese beetle populations are therefore not likely to be greatly affected by the cold 2013-2014 winter.



Z. Szendrei and R. Isaacs 2006. Ground covers influence the abundance and behavior of Japanese beetles. Environmental Entomology 35:789-796.

Japanese beetle. University of Illinois Extension IPM Article.

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