At Last! Fireflies and Japanese Beetles

Adult Japanese beetle photo by Laura Iles
Japanese beetle adult.  Photo by Laura Jesse Iles.

The cool temperatures and rainfall have delayed planting, flowering and insect emergence, but two of our late-spring arrivals are finally ready to put in an appearance; the Japanese beetle and lightningbugs

Japanese beetle adults have been observed in southern and central Iowa.  We don’t know what the population abundance will be this year but they here, though off to a slow start.

The slow start to Japanese beetle emergence was discussed in the June 17, 2019 Integrated Crop Management News.  The Growing Degree Map included in the ICM article suggests it will take many warm, dry days before adults emerge in northern Iowa. 

See our HHPN Encyclopedia article on Japanese beetle for details on appearance, damage and management options. 

We continue to monitor the locations of the Japanese beetle in Iowa.  See map below.  If you observe adults in a county where they have not yet been reported, please send images to  List the location and date in your message.

Map of Iowa showing current reported distribution of Japanese beetles


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