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Harsh Winter Likely Didn’t Slow Japanese Beetle

May 12, 2014

Farmers and home gardeners probably should not expect a respite from a voracious pest.

The Japanese beetle is an oval-shaped, metallic green insect that remains in the region during the winter months. Its numbers probably won’t be hurt by this winter’s especially cold conditions because it’s good at developing survival strategies.

In the fall and into winter, they can shed excess water and produce more sugars in their cells... as a natural anti-freeze.
The Japanese Beetle
Credit University of Illinois Extension

“Unfortunately, (their) c-shaped larvae have the ability to burrow very deeply into the soil. And so they can actually burrow below the frost line,” said Angie Peltier, Commercial Agriculture Educator with the University of Illinois Extension in Monmouth.

She also said sod and snow cover have a moderating effect on soil temperatures, and the insect has other ways of staying alive during the winter.

“In the fall and into winter, they can shed excess water and produce more sugars in their cells. And those combined act sort of as a natural anti-freeze,” said Peltier.

She said entomologists have found high rates of survival among the Japanese beetle even in states that are extremely cold every winter, such as Minnesota.

Peltier has written about the Japanese beetle in her blog Hill and Furrow, and her colleague Rhonda Ferree writes the blog Japanese Beetle News.

Peltier said the U of I Extension will monitor Japanese beetle emergence at its Northwestern Illinois Agricultural Research and Demonstration Center outside Monmouth and elsewhere throughout the state. She said they’ll have a better idea of the survival rates by mid-to-late June.

Peltier said the Japanese beetle feasts on all types of foliage including ornamental plants, row crops, and fruits and vegetables.