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Springtime Grub Issues

May 9, 2010

I was wondering if anyone else out there is experiencing grub problems this spring. We have had some digging for about 2 weeks now. We examined the turf to find numerous grubs like you would in the fall. I suspect that the amount of grubs might be attributed to the Japanese beetles that we experienced in mass numbers last year for the first time. I would be interested to hear from anyone that is or has experienced this problem before.

PS caught my first coon last night…..

Randy Moeller
Golf Course Supervisor
City of Muscatine, Iowa 52761


Dare I say it. Can we get a little rain?

October 18, 2010

We are just past the halfway point in October and some parts of the state have yet to receive any considerable rainfall this month. After being bombarded with rain during the summer months, the Des Moines area has received a measly 0.03 inches of rainfall so far in October. Their last considerable rainfall event took place on September 25. Depending on what happens the remaining 14 days of the month, October could go down as one of the driest on record. Irrigation systems that didn’t get much use during the rainy summer months are surely being used during this stretch of dry weather. The picture below from the National Weather Service shows that a good chunk of the Midwest is experiencing below average rainfall for October.

There hasn’t been too much activity (as far as stresses go) at the research station. We still have dollar spot working in some areas and rust and powdery mildew are showing up on Kentucky bluegrass. Grub damage at the station seems to be less this year compared to years past.

Other than the droughty conditions, the fall months have been conducive for turfgrass growth and recovery. Soil temperatures are holding steady in the high 50’s low 60’s. Those putting down natural organic fertilizers yet this fall, remember that those products require microbial activity to release the nitrogen contained in the product. Microbial activity usually ceases at 50 degrees. The dry conditions could also affect post-emergent herbicide applications as uptake and translocation are not as effective on drought stressed weeds.

I’ll leave you with some pictures of fall.

Regardless of the weather conditions, poa always seems to find a way to thrive.

This maple provides brilliant fall color on the north side of the ISU campus



November 10, 2012

Here is another post from Larry Ginger of "American Lawn Care" in Des Moines.  Larry has been keeping us updated on late grub damage and fall seeding on lawns that he manages.  Below are some pictures from Pleasant Hill, Ia showing active grubs on November 9.  I am going to have to change my teaching notes on this.  Generally the grubs have burrowed deep underground by this time, but here they are in November.

Larry also reports an 800% increase in his fall seeding business.  He is using a three-way blend of Falcon IV, Five Point and Six Point turf-type tall fescues.  He will send us some pictures of newly seeded lawns next week.

I have also been seeding areas that had been established to Kentucky bluegrass in the past, but were lost to the drought this summer.  I have tried turf-type tall fescues as well in some areas and will report the success with this next season.  My main concern is how well they will blend with the Kentucky bluegrass remaining on the area.

Figure 1.  Active grub on November 9 in central Iowa.
Grub Damage

Figure 2.  Grub damage.



October 30, 2012

Here are a couple of pictures from Larry Ginger of “American Lawn Care” in Des Moines.  It is of grub damage in Urbandale, Ia from October 24, 2012.  I believe that this is a Masked Chafer grub.

While grub damage is not unusual in Urbandale, the timing is somewhat unusual.  I would expect to see first damage in August and I would expect the damage to be over by early October.  At that time, the grubs generally burrow down about 6 inches in the soil to overwinter.

This is unusually late to see active grubs, but there have been a lot of unusual things this year.  I have had a couple of other calls on late grub activity.  If anyone else is seeing it even later, send me some pictures and some information on it siting so that we can keep a record of it on the blog for next year.

Grub Damage

Grub Damage



August 15, 2012

Here is a post form Neric Smith, Landscape and Turfgrass Instructor at Indian Hills Community College in Ottumwa, Iowa.  It is my first contact on white grubs for the season.  They generally begin to appear in early August and continue into October.  If anyone else is seeing them, send me some pictures.  I'm counting on less grubs this season because of the heat and the dry conditions, but I may be wrong.

Neric has a growing turf program at Indian Hills.  For those of you from that area that may be interested in his program, here is his contact information.

Neric D. Smith
Landscape and Turfgrass Instructor
Indian Hills Community College
525 Grandview Ave.
Ottumwa, IA 52501
Office Phone: 641-683-5194


From Neric:

The Heat is one thing to deal with, but add white grubs and things get worse.  Attached are pictures of grub damage found this week August 5th on a softball field here at Indian Hills Community College in Ottumwa, IA.  It is a Kentucky bluegrass field that was treated on June 4th with a granular fertilizer and Merit insecticide.  The field does have plenty of thatch and the application was at the low rate of product.  It doesn’t take long with 100 plus temperatures(yesterday) for things to turn brown even with syringing.  Dylox will be applied and life will go on!  Just thought that I would share and see if anyone else was seeing white grub damage yet? 





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


Early Billbugs and Masked Chafers in Ames, Iowa

June 27, 2016

Bluegrass billbug damage and small Masked Chafer grubs began to show up on June 25, 2016 in Ames.  This is very early for this area.  The billbugs were at Veenker golf course on campus.  The small chafer grubs were on a bentgrass green at the research station.  The chafers are too small to do direct damage at this time, but birds are tearing the green up looking for them.  We treated with Dylox shortly after we saw them.


This is the damage from billbugs in the rough at Veenker golf course in Ames.

A close up of the feeding damage.  Notice the hollow stems at the base.


Billbug grub from the damaged area.

The billbugs are surprising mature for this early date.  I generally wouldn't expect to see feeding damage and grubs that have emerged from sheath tissue for another 3 to 4 weeks.  If you are in lawn care, you may want to scout for them early.


These are the small masked chafer grubs at the research station.  Birds are causing significant damage to the greens surface and we had to treat.


For more information on billbugs see an earlier blog at