It's waaay too late to kill them. They stopped feeding in July or early August. Spending money on Grub Ex now would be a waste of money. The damage they cause seems to not become visible for many weeks after they have stopped feeding.

Where do you live?
What kind of grass do you have?

If you have fescue then you need to reseed or resod immediately. If you have almost any other grass, it will refill next spring.

Grubs do not affect every lawn and they do not affect the same lawn every year. Late next spring watch your porch lights for signs of abnormally high populations of June bugs or Japanese beetles. If you get those beetles in large numbers, then treat for grubs in June. If you wanted to be extra careful and not treat unless you have grubs, in June you could dig up a square foot of sod. If you see more than a dozen grubs, treat. If you see fewer than a dozen, don't waste your money.

There is a problem with using insecticides and a special problem when using one is completely ineffective against the pest you want to control. The problem is that one of the large classes of beneficial microbes in your soil is microscopic insects. When you disrupt such a large class of critters, the health of your soil can decline quickly. For that reason I like to use organic controls. The organic insect controllers are all disease based. There are certain diseases which affect only insects. If you apply one of those to the soil, the recovery is much quicker, because everything is natural...except the amount of insect disease microbes in the soil. But the soil does recover without any Herculean effort.

Hi and thank you for replying ;) I live in Pittsburgh, Pa and I have KBG and fescue and rye, we sodded in October of 2008 so this is the grass they had left for this time of yr. I was out there earlier and noticed it looked stressed and brownish so I lifted it up and it came right up like a rug ..ahhhh I almost fainted Literally I am so anal w my lawn...I want to treat it I am afraid they will do more damage my lawn is thick and green and the side of the lawn is where this problem is I was getting dark so couldn't check the rest of the lawn...but I did go back out w a flash light and found within a few feet like 5 or 6 different sizes but 4 fat ones...Nasty little critters..X , Do you think I can sod that area after I apply grub ex? I really don't want any more damage...I'm beyond upset..also we never get beetles here or june bugs, so how in the world did they pick my lawn to feast on????

Grub-ex won't work in September, the grubs are second instar. Kill rates will be about zero.

Merit, however, will help and will kill the grubs. If you have more than ten per square foot, it's time to pull out the Merit to get rid of them. I had to do that one September about...oh, seven years ago. A thousand square feet of turf floated as the root systems were completely eaten. Grub counts were in the hundred per square foot range. It was disgusting.

Eating or not, the Merit will kill second (and even third) instar grubs. Usually grub's root consumption doesn't stop on northern lawns until frost, when they migrate deep enough to be below the average freeze zone for Pennsylvania. Sometimes, like last year, we get lucky and have a really hard winter that freezes the soil below the hibernation line and they die. I wouldn't count on that, though.

Hi where can I Buy merit? and is it granular? Thank you so much ;) are you in Pa also??

A lot of big box stores will have it, but call. If not, most landscapers and most smaller garden shops can order it for you. I attached an example link but, at this concentration, only about 1.6 pounds per thousand square feet is required. It's not likely you need a bag this big!

This is a granular, and I used a granular in a very different looking bag (I don't remember the brand name). Grub numbers went from sickening to zero in a week (probably faster, but I didn't look).

Once the grubs are dead, you can restore that grass.

"Floating" turf like you have can be re-rooted, and there's plenty of time to do so. In this one case, break the watering rule and water to always keep the soil damp. That will encourage the roots to spread.

Feed lightly but often--lacking much root, the grass can't absorb much at any one time. Feeding about a quarter rate every week is actually going to be optimal here, but half rate every 2 weeks through the end of the season will work fine too.

Root growth will continue until ground freeze--probably late December or so, but you know as well as I do how much that varies. :-) By late October it should be re-rooted well enough to stop the floating, though.

And yep, I'm in the Lehigh Valley, which is a different climate than you have. But I'm familiar with the Pittsburgh area, so that's not a problem.

Here is a link that might be useful: Merit Insecticide

Thank you so much ;) I just called the local nursery and I am getting a bag today and spreading it later this afternoon he said he has some nice sod their as well, should I wait to sod? So these pieces of grass have been dead? It was all super green and I mow my lawn high, but last week did it a tad bit shorter since fall is here tomorrow and the cooler nights, I couldn't find a Load of grubs that is the Odd thing only like about 3 big ones and a few smaller but you could slip my hand under and it would go right through I almost passed out LOL :( Ugh this is so annoying, I take such good care of my lawn too. Thank you so much!!!!! ;)

I think I'd poke around for more grubs if I were you, before using Merit. If you need it, there's no choice. If not, it's going to do a number on the micro-arthropods in the soil and I'd try to avoid it.

If you roll back the turf that floated, there should be enormous numbers of grubs under there if that's your problem (you may need to roll back a bit of turf that still looks good).

For now, wait to sod about a week post-Merit. The stuff won't hurt the sod, but the living grubs will have a few days to do damage. And you may not have to sod if you can get the roots to re-establish themselves on the old turf, but without photos I can't tell you if it's likely to happen or not.

I bought the Bayer 24 hour grub killer, that is what he said to get it and water in well tonight, I just looked again and you can pull the grass back and I can put my hand easily under it so I would say yes it has to be the grubs what else? also are you saying this could damage my lawn?? My lawn is thick and green :( I would be devastated I am already freaking out ....Thanks again

Merit has no visible impact on grasses at all, so no worries there. It's more a worry that it'll damage the insect populations (that are normal and healthy) in your lawn. Over the long term, that can present some challenges.

However, if you have grubs, you have to get rid of the grubs or they'll completely destroy your lawn. On balance, using the Merit is a better choice by far.

Hi again I took a few pictures for you since you have been a Huge Help to me ;) Here is one

Here is another it won't let me put two pictures same time

And here is the rest of my Lawn seems to look healthy I yanked on some spots some are a little dry but I think its lack of rain here in Pittsburgh lately. Thank you again for all your help :)

That's very minor grub damage, minor enough that I can't really tell you have grubs. :-) That lawn, overall, looks great.

If grubs it was (like I said, it hasn't gone far enough to look like characteristic grub damage, but for those of us who pay attention to our lawns, it wouldn't), the Merit just took care of it. I hope you treated the whole lawn just in case as grub damage can take weeks to show. If not, I'd advise going back this weekend and getting enough to do so.

In a few days you should notice the existing grubs turning a sort of brownish color and no longer moving. They're dead and turning into organic matter for the soil.

Keep the soil moist and I don't think you need sod, it should recover nicely although it may not do so fully this fall. I'd advise watering in the morning to avoid going through the night with damp blades, which would invite fungal infections. Fortunately, fall isn't usually a period where those run rampant, but it would hardly be the first time it happened. Better safe than sorry.

Next May (yes, May), put down Grub-X. It's a much more mild strike than Merit, will protect you from grubs for the rest of the year, and won't impact other insect populations or earthworms. Post my little disaster, I shield my grass every year in May and haven't had a problem since (and far fewer Japanese beetles as well).

Thank you so much ;) I will post in a few days and let you know how it is going! I watered for an hour and 1/2 around 5 so yea I was afraid of fungus w later watering but it had to be done. The water didn't seem to get down into the soil when I checked after I watered...:x I hope it seeps down into it, I will water in the morning for an hour, there are part of the healthy lawn that looks yellowish kind of scary :/ I Hope to god it stays healthy. will be in touch....Thanks again

Oh yea Yes I did the whole lawn :)
Thanks so much!!!

Late watering once won't be a problem, the grass gets dew, after all. And that, around here, forms before midnight in late September.

The water should soak in, but check. With the dreadful weather the entire state's had this last month, it could be that the soil is simply extremely dry and a little hydrophobic. That usually goes away the second watering (but if not I have a solution for it--put some shampoo of whatever type in your hose end sprayer, spray about 3 oz per thousand). Then water. The soap breaks the surface tension and the soil soaks it in much more easily. I like Suave as it's cheap and the apple scented stuff is nice.

Once the weather breaks cooler again, which looks to happen around October 3rd, watering frequency can go way down. Moist soil is sufficient, it doesn't have to be saturated. More normal rainfall looks like it resumes then as well.

Very gentle feeding of the damaged areas will also accelerate the repair, but don't overdo it. Like I said earlier, quarter rate once a week is optimal. Areas where there's no visible damage (even if there is some down below in the root systems where you can't see it) don't require extra feeding.

I'm still not convinced it was grub damage. When you say you take such good care of your lawn, what does that entail? Specifically...

Your mowing looks fine, so no question about that.
How often do you water and for how long?
When were the last two times you fertilized and what did you use?
Have you used any fungicides, herbicides, or other insecticides this year? If so, what was it?

I don't fertilize all summer only spring hence I don't want to get summer patch as I had that before and had to rip my entire lawn out and get sod in 2008, I went to look outside and pulled back those dead areas that are like a rug and I see NO grubs just tiny little normal bugs in the soil...I haven't watered a lot lately since the cooler nights here in Pitt, but we are lacking water a lot..I used the treatment and watered it in for a few hours within the 24 hour window, I also watered this morning too for an hour. I aerate every spring and use a turfbuilder/crabgrass control but I wont be doing that next yr we have NO crabgrass and it burned parts of my lawn the spreader leaked, so just turfbuilder after winter, and a weed and feed and that is all I use to be honest...

and no I only used this bayer 24 hour grub control, ;) that is all.. I use the guidelines for making summer patch stay at bay, NO over fertilizing, always Mow High which I think looks best anyhow..what do you think did it then I found like 6 grubs in those areas where its all coming up :x, I will re sod soon..I don't like to look at dead grass patches.. Yikes

morpheuspa, HI ;) I wanted to tell you I was outside earlier today and lifted another area of the lawn way other side where it looked dried out and it came up easily and the roots are eaten and I found a sluggish/almost dead grub...so I am pretty sure that worked ( praying ) Do you think I should SOD tomorrow I didn't mow my lawn yet I usually do it on Thursdays lol :) I am just sickened when I look at that area esp that is in the pic I sent, :( makes me sick.. I was going to mow tomorrow and go buy some pieces of SOD and lay them..also I have alittle patch of looks like poa annua or some kind of tall fescue that I don't like so was going to cut that out too ...can you tell i'm obsessed a tad bit. will keep you updated, Hope your well..and enjoy the weekend here in Pa going to be 80 all weekend. ;) ( p.s. I think I am the only one on my road who wants rain LOL ) rain is Our bestfriend

>>Do you think I should SOD tomorrow

I think I'd hold off at least a week post-Merit, absolute minimum. Fortunately, sod can go any time up to within a month or so of ground freeze (really, even closer) and do just fine.

Reason being I don't want you to dilute the effectiveness by removing Merit-treated soil until the problem is solved. If it was grubs, that is, but we'll run with that until proven otherwise.

hmmm what else could it have been that would eat the roots of the grass like that then? if it were a fungus it would be all over and I have a book of lawn diseases and don't look like any of them, maybe a little like summer patch but its so scattered and the lawn comes up like a blanket in those areas..No roots connected to soil ...

>>hmmm what else could it have been that would eat the roots of the grass like that then?

The vast majority of root eaters will be insects, and the Merit probably took them out. That's why I wasn't terribly concerned about its use.

Root nematodes are a possibility, and in that case I'm not real sure about Merit's effectiveness. But if the grass recovers (or the new sod doesn't go), we've just proved we cured it.

HI there, I Just ripped out that area pretty good, not all of it but most in that area and there was just dirt exposed and I took a knife and dug deep and found like 5 small dead grubs and like 10 FAT white ones that were still living but they were pretty deep...I killed them all w my hands LOL and got 2 pieces of sod and put a little more bayer 24 hour grub killer down on the dirt not a lot just sprinkled it and a little over the rest of my lawn, we are in a drought here in Pa my lawn is dieing out near the corner I am watering as i'm typing thoroughly for the sod as well...and I had watered it for 30 mins..UNREAL all those grubs so like there were a lot in that area from last weeks that I found and todays...Ughhh heres the after pic Of the sod all fixed for now..now I need to keep up in may w the grub stuff, DO you think my lawn is now safe this October to come?? I cant bare to see anymore damage

Actually no, you do not need to keep up with grub control. Grubs are a rare occurrence. In my opinion you did not have nearly enough grubs to have caused that damage. You looked and looked and did not count enough. And just because you had a small number of them this year has nothing to do with future grub populations. The grubs hatch into beetles and fly away. If you are still concerned next June, and I suspect you will be, please dig up the lawn like you did this year and look for grubs. If you see fewer than a dozen per square feet, then you do not have a grub problem. You might have other problems, but not grub problems. If you see a dozen or more, then go ahead and apply whatever you want. And then, two weeks later, follow up the insecticide treatment with compost at a rate of 1 cubic yard per 1,000 square feet. By using the compost you can replenish the microscopic insects killed by the insecticide and your soil should not suffer any longer than it might otherwise.

Reread morph's earlier post about his experience with grubs. He had hundreds per square foot. You had 3. He did not say it but he does not routinely treat his lawn for insects. Routine use of insecticide is a fast track way to ruin the health of your soil. The Scott's people will be happy to sell you more and more chemicals to fix it (it won't) or you can use compost and be done with it.

>>He did not say it but he does not routinely treat his lawn for insects.

Actually, I use GrubX every year now as Japanese beetles are always attracted to the green, healthy lawn among all the dead ones. So I get the beetle eggs for miles around as females fly in to lay. And the gardens, being one of the few in the area, are rather attractive to them as well.

GrubX is weak enough that I don't feel too awful having to use it yearly, although I still don't like it.

Other than that, I don't require any insecticides and don't use them.

The problem I have with products like Merit is that it is a systemmic insecticide. It impregnates itself into plant tissues. It is this class of insecticides that is doing extreme harm to bees - we've all read the stories. What I found is that within about the very same price range of the systemmics, I can apply the appropriate type of nematodes (usually needs temperatures above ~ 50 degrees F) which will attack the grubs without harming anything else. And when combined with milky spore, particularly for lawns, the nematodes help carry the milky spore into all areas of the lawn, giving you better long-term control, for many years, for all possibility of grubs in your lawn.