Brown/damaged patch in lawn - grubs?

thinksincode

I've been concerned about some brown dry patches of grass in my lawn. I had assumed it was just not getting enough water, but yesterday when I was pulling some weeds I found the extent of the damage.

Basically the whole area just rolls up like a mat, leaving just bare soil. I saw plenty of bugs in there (mostly ants), but I didn't see any of those white grubs. I saw some bugs that looked like worms coiled up in a circle (not a great description). Is this grub damage? Looks similar to what I've seen when Googling it. Here are some pictures of the brown patch, and how it looks when I pull the grass back.

Thunder Chicken

Have you seen any Japanese beetles flying around your yard? At this time of year they should be in their adult stage, so you won't see grubs in the ground. You might be seeing grub damage from earlier in the summer before the adults emerged. The grass may have survived the grubs but died in the heat because of the root damage.

You'll want to spread some milky spore before the next generation grubs start munching on the roots again (usually in late summer and fall). That is also when you should check again to see if grubs are present. The grubs will ingest the spores which will kill them, and the spores grow in their bodies and will continue to keep the grubs under control.

You can overseed in the fall, hopefully the grubs won't do too much more damage before the milky spore hits them.

thinksincode

To answer your question, we have had quite a few beetles eating our flowers, but I don't think they're Japanese beetles - aren't Japanese beetles the ones with the metallic green color? The beetles I've seen look like them but are all brown. Here's the only picture I could find of one that my wife snapped.

Thunder Chicken

I forget the ID of that particular beetle (I don't think it is a Japanese beetle) but it is about the same thing. It has a grub stage that eats your grass roots. Milky spore will work against them as well.

thinksincode

I did a little digging around and it looks like these are Oriental beetles: http://bugguide.net/node/view/23058

thinksincode

So my other question is, how do I repair it? Just rake up the damaged area and put down some seed?

Thunder Chicken

Yes, that is pretty much all you can do. Some of those patches may not be dead, just dormant because of their shallow damaged roots. Hopefully the milky spore will take before they do further damage this fall. The grubs need to be feeding to intake milky spore. Once the lawn is innoculated with the spore it should last for a few years.

This fall I'd overseed a bit heavier than the instructions indicate expecting some loss to the last grubs, then I'd be ready to overseed again in the spring after you know what made it through the winter. After that you should be in good shape.