As reported last year, Scott County is our only known location of Japanese beetle infestations in Iowa. (see Horticulture and Home Pest News, July 21, 1995, page 113). While Japanese beetles are occasionally caught in Iowa Department of Agriculture and Land Stewardship monitoring traps at other locations throughout the state, no established populations have been reported outside of Davenport, Bettendorf and Le Claire.
Therefore, we repeat our request -- PLEASE REPORT NEW COUNTY RECORDS OF JAPANESE BEETLE IN IOWA BY SENDING SPECIMENS.
Emergence of Japanese beetles was reported last week in southwestern Illinois. Therefore, now is the time to start watching for this pest. Japanese beetle adults feed on a tremendous variety of plants but they prefer roses, raspberries, crabapple and grape.
Adult Japanese beetles measure 1/3 to 3/5 inch in length. The head and thorax are shiny metallic green and the wing covers are metallic-bronze. The abdomen is marked with a row of six white tufts of hair along each side. The immature stage lives in the soil as a grub and feeds on grass roots. One generation occurs each year and adults emerge during June and July (and a few in August). They can live for several weeks and may be present and cause damage for the entire summer.
Japanese beetles often feed in clusters and can cause heavy defoliation in a short period of time. Feeding injury appears as "skeletonizing" because the beetles remove all succulent leaf tissue from between the leaf veins.
See the newsletter article cited above for more information on control options. Collected samples should be preserved in alcohol and mailed to Extension Entomology, 109 Insectary, ISU, Ames IA 50011. Please include collection locale with the specimens.
This article originally appeared in the July 12, 1996 issue, p. 116.