Pest Alert №4 — Japanese Beetles

Japanese beetles (Popillia japonica) are not welcome, but we have to deal with them each year don’t we? Our first initial sightings of adult beetles in Chicago started to trickle in last week. Today, one held still long enough (snap) with the help of a superintendent’s hand. That snap was the photo. Thank you AD

Image 1. Andy Dauksas, GCS, Glen Oak CC, holds an iridescent Japanese beetle. A grower with a steady hand. Settle, Jun 14, 2021
Image 2. Japanese beetles love to eat about 350 different kinds of plants in the landscape. Here we check one of the all-time favorites of basil (roses are another). Settle, Jul 14, 2021
Image 3. No signs of feeding (skeletonizing of leaves) which is good news. It means current populations are low and whether or not that continues = requires scouting. Settle, Jul 14, 2021

Importance. Japanese larvae (grubs) feed on the roots of all turfgrasses. They have become the dominant grub population in the landscape that negatively impacts golf courses, lawns, parks and cemeteries in the northeastern US. If preventive measures are not taken, significant root loss and turfgrass damage can occur by the fall.

Interestingly, a majority of the damage isn’t due to a loss of roots and associated wilt and browning of turfgrass areas. Instead, it is caused by the small mammals that feed on the grubs like skunks and raccoons. It you haven’t experienced imagine a mini-trencher digging up areas of your lawn in the middle of the night while you are asleep in say late September.

Reference. It turns out our neighbors to the south, Purdue University, had reported 1st sighting of Japanese beetles about a month earlier (June 17). Which makes sense as they likely have experienced warmer conditions thus far vs Chicago suburbia = we all gain insights by sharing pest information.



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Dedicated researchers and turf pathologists working for golf course superintendents in the Chicago area.