No. 17 Article 1/July 30, 2010

A Blizzard of Small Yellowish-Brown Moths Reported Across Some Areas of Central and Northern Illinois

It continues to be an odd summer in the entomology arena for much of Illinois. Corn rootworm and Japanese beetle numbers are down. Overall rootworm pressure is about as low as I have observed in the past quarter-century. Yet some insect oddities are occurring, and I have encouraged soybean producers to be vigilant in scouting for new stink bug species in their fields. This past week, there have been numerous reports of small yellowish-brown moths across much of central and northern Illinois. Jim Donnelly, Green River Seeds, Bureau County, was kind enough to provide an excellent photograph.

Suspected celery leaftier moth. (Photo courtesy of Jim Donnelly.)

Many individuals have indicated that these moths are numerous in the evenings near porch lights and are very noticeable as they strike vehicle windshields. Others have seen them while mowing yards and ditchbanks, with hundreds of them being kicked up ahead of the mower. When I first looked at the moth photos being provided to me, I thought of the European corn borer. However, these moths are approximately half the size of corn borer moths, and the wing markings differ somewhat.

I circulated a photo to some of my entomology colleagues in the north-central region to get other opinions on the identity of this species. Some of the input I received points in the direction of the insects being celery leaftier (Udea rubigalis) moths. In 1996, Marlin Rice, long-time extension entomologist at Iowa State University (now with Pioneer Hi-Bred), published an article on this species in the Integrated Crop Management newsletter. He reported that the moths were very abundant in soybeans and corn in late September and throughout much of October.

We are witnessing high densities of this suspected species much earlier in the season, which suggests that the surge may just be one of the earlier generations. According to Marlin's information, this lepidopteran feeds on many species of plants, such as "cultivated flowers, weeds, and vegetables including beets, spinach, beans, and celery." Fortunately, this species is not considered an economic pest of soybeans or corn.

It will be interesting to see if we observe a later generation of this insect as we get closer to harvest. Thanks to everyone who provided photographs and reports.--Mike Gray

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