No. 7 Article 2/May 21, 2010

North-Central Entomology Observations: Sporadic Black Cutworm and Cereal Leaf Beetle Infestations

On May 17 I participated in a teleconference where extension entomologists from around the north-central region shared observations of insects in field crops. My assessment: aside from sporadic black cutworm infestations, so far it has been a relatively quiet spring on the insect front. Soybean aphids may also get off to a very slow start this year. The delays in planting soybeans will present challenges for the few soybean aphids leaving buckthorn in search of emerging soybean plants.

Ron Hammond, an entomologist with Ohio State University, reported that in some areas of southern Ohio, spraying was occurring in wheat fields for cereal leaf beetles. The adult cereal leaf beetle has metallic bluish-black wing covers and reddish-orange legs and thorax. The most significant damage is caused by larvae feeding on the upper leaves of wheat plants. Larvae, which resemble slugs, remove the epidermal tissue of leaves in long strips. The sluglike appearance, created with moist fecal material created by the larvae, is thought to serve a protective function against predators or parasitoids. Feeding may occur over a 10-day period. Wheat fields with extensive feeding take on a "frosted" appearance.

Cereal leaf beetle adult (Courtesy of Robert Bellm, University of Illinois Extension).

Cereal leaf beetle larva (Courtesy of Robert Bellm, University of Illinois Extension).

Producers should scout their fields and consider a rescue treatment if a combination of eggs and larvae averages 3 or more per stem. The eggs (1/32-inch long) are yellow to yellowish-orange and elliptical in shape and can be found singly or in small chains near the midvein of upper leaf surfaces. So far this season I have not received any reports of cereal leaf beetles causing problems in Illinois wheat fields; however, if you have observed economic levels of this pest, please let me know.--Mike Gray

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