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August 10, 2010

In an earlier post on possible June Bug damage, I showed some pictures from Raccoon Valley Golf Course in Jefferson, Jay Goughner, owner and Supt. They showed what appeared to be June Bug damage in rough on a major part of the course. I stopped there last Friday and picked up some samples of the grubs for verification. This would be the first major June Bug damage that I have seen in my 31 years here and I wanted to be sure that was the problem. Below are pictures of the rough and a couple of insects in the soil.

Unlike the Chafer and Japanese Beetles, which do their damage in August to Oct., the June Bug does its damage in mid summer, July to early August.

The fairways in this picture were treated with imidacloprid (Merit) and the rough was not. It obviously worked on the fairway. If you have the problem now, you will have to treat with a Dylox or a similar compound and water it into the soil. That is very difficult to do.


The best way to identify the larvae is with the raster pattern. See the pictures below of a series of species.

I took the samples to Dr. Don Lewis in the entomology department on Monday. Here is what we saw under the microscope. These are June bugs (Phyllophaga spp)(also called May Beetle in some areas).

I have also had some other calls on suspected damage in Des Moines and other areas in central Iowa. If you have seen them, let me know.



July 22, 2010

Here is a post from Jay Goughnour of Racoon Valley Golf Course in Jefferson, Ia. While grub damage on Iowa golf courses is not unusual, the problem is generally from Masked Chaferes and occurs in August to October. The problem below happened in mid July. The grubs on the site are much larger than chafer grubs and appear to be June bugs. June bug larvae feed earlier than chafers, usually mid July, which coincides with this damage. June bug damage is fairly rare, however, and I have seen damage only a few times over my 31 years here in central Iowa from this species, whereas I can find chafers every year. I hope this isn't a trend. If anyone else has seen early grub damage from large grubs (1 inch in length), let me know.

Because of their size, it does not take as many June bug grubs as chafers to damage turf. While we normally look for 20 to 30 chafers per square foot to damage turf, June bugs can damage turf with populations of 5 or 6 per square foot.

Racoons love to dig up turf for these grubs. I would be worried if my golf course was named Racoon Valley.

Nick Christians

Jay writes:

July 20th. Fairway on the right was treated with imidacloprid for grubs. The rough on the left is untreated. Pretty dramatic difference. Looks like the larvae from June bugs instead of the european masked chafers I'm used to seeing.

Jay can be reached at