No. 13 Article 3/June 22, 2007

Get Ready for Japanese Beetles and Western Corn Rootworms

(Originally published as an Alert on June 15, 2007)

The line on Japanese beetles in southern Illinois has already become "ridiculous," a word we used to describe the numbers of beetles being captured in traps in southern Illinois in 2006. Ron Hines, FS seed agronomist for Growmark's southern region, has reported new 1-day and 3-day records for captures of Japanese beetles in the trap in Massac County--almost 49,000 in 24 hours (June 14-15) and almost 102,000 June 12 through June 15! The trap operator already had switched to the larger container, which now needs to be emptied twice per day. In addition, he has an insect disposal problem.

These unprecedented numbers of Japanese beetles emerging this early in 2007 does not bode well, for obvious reasons. All of these beetles are going to be hungry, and injury to the crops they infest probably will be significant. Corn and soybean growers, beware.

It's apparent that Japanese beetles survived the winter very well in southern Illinois counties, so now those of us in central and northern Illinois are wondering what's in store for us. It's worth noting that a handful of people already have found the occasional Japanese beetle right here in east-central Illinois.

Given our prediction of early emergence of western corn rootworms in issue no. 12 of the Bulletin (June 15, 2007), the beetles decided to show up right on cue. Joe Spencer, research entomologist with the Illinois Natural History Survey, observed newly emerged western corn rootworm adults in his plots just northeast of Urbana on June 14. So now we will have both western corn rootworm adults and Japanese beetles vying for corn silks when they emerge. Until that time, expect to see significant leaf feeding, particularly by western corn rootworms.

With insects starting to rear their chitinous heads while corn and soybeans are suffering from a lack of moisture, we will have to anticipate adjusting control decisions on the fly.--Kevin Steffey and Mike Gray

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