Question
Zip code:  12148
Thanks for taking the time to help me.
Last summer/fall, grubs did some major damage to my lawn.  I had been using the Scott's Step 4 Program and was happy with the results I have had the previous three summers (green, healthy grass).
However, I never added any grub treatment, because I didn't have any problems (or so I thought).  After seeing a stubborn skunk tear up my back lawn, feasting on the grubs this past September, I decided to put down the final Scott's treatment (Step 4), and address the damage in the Spring.  What steps do I take to repair the damage that was done?  I could literally peel back over 60% of my back lawn--the damage was that extensive.  Do I peel it and re-seed, or will the damage lawn re-grow strong roots with the proper treatment?  What is the proper treatment?
Thanks for any advice.

Answer
Good afternoon Pete:
It seems that grubs love the tasty roots of healthy green turfgrass. People that usually pay no attention to their lawns have few grub problems.
White grubs are larval or immature stages of beetles and the two major problem species are Japanese and masked chafer beetles. Both beetles fly and lay eggs mostly in June and July. The eggs hatch by early August and the larvae (white grubs) begin feeding just below the soil surface on the roots of grasses.
Most of the feeding damage occurs from late August to mid-October in your area. A damaged root system means reduced ability of grasses to take up water. If the root damage is severe, the grass will turn brown and die. It is normal to find one to five white grubs per square foot. When the weather is cooler and soil moisture is good, 20 or more grubs per square foot may be necessary to cause damage.
Tall fescue is seldom damaged by white grubs. During the mid-August and September feeding period, tall fescue usually is able to replenish (re-grow) its root system at a rate sufficient to counteract grub feeding. During that same feeding period, Kentucky bluegrass roots are not re-growing.
Based on that scenario, consider renovating heavily damaged Kentucky bluegrass turf (if that is what you have) with tall fescue. Tall fescue has superior drought resistance, shade tolerance, traffic tolerance, insect and disease resistance.
Withhold irrigation as much as possible in June and July, but if grub damage starts to occur in late August and September, water frequently.
Apply all, or most, nitrogen in October, November and December. Heavy nitrogen fertilization in the spring and summer will decrease root growth, increase turf stress and accentuate the damage caused by grubs during September and October.
Raise your summer mowing height to 3 to 3 ?inches. This discourages egg laying in June and July and usually results in a better root system.
The only time of year that white grubs damage turf is from late August to mid-October. Grubs are also present in the spring and early summer but spring grub treatments are usually unnecessary because killing grubs in spring does not normally reduce the August-September population of grubs. Egglaying beetles can fly considerable distances, from nearby properties, to re-infest grub-free turf.
During late August through mid-October, watch carefully for signs of irregular patches of  brown turf. Grab a handful of the brown grass and see if the turf pulls loose from the soil like lifting a carpet. Unless birds have already stolen the grubs, the C-shaped white grubs, from 1/4 to 3/4 inches long, will be obvious on the soil surface and the soil will be very loose. Check several suspected spots.
Because you have had serious turf damage from grubs in the last year they are likely to return to the same turfgrass areas this year.
If you observe grub damage during late August, September or October, the best rescue treatment is a product containing trichlorfon (Dylox/Bayer Advanced Lawn 24-hour Grub Control). When applied, this insecticide MUST immediately be watered in with about ? of irrigation or rainfall in order to get the chemical into the soil where the grubs are feeding. Granular formulations are usually more convenient and sometimes more effective, especially if irrigation cannot be applied immediately after treatment. Irrigation or rainfall just prior to insecticide application will generally improve the efficacy of the insecticide.
Because white grubs damaged the turf in the last year, consider a preventative treatment with one of the following products.  They persist in soil for several months, allowing flexibility in timing of applications. Rainfall or irrigation is needed to water-in the product, but the timing is not critical.
Merit (imidacloprid), Bayer Advanced Season-long Grub Control. Merit disrupts the insect's nerves in a selective manner. Best to apply from mid-June to mid-July, and not later than the third week of July.
Mach 2 (halofenozide), Scotts Grub-Ex. Mach 2 mimics a natural insect molting hormone, causing a premature, lethal molt. Best to apply from mid-June 15 to mid-August. It is seldom effective after turf damage begins occurring that is when the white grubs are already large.
Do not buy more of these pesticides than you will need and do not apply more than is required. Before using any pesticide, read the label and follow all precautions!
Unfortunately, there are no proven biological products that will provide reliable control of grubs. Milky disease spores can be purchased but they have not been effective in university tests. Also, milky disease has no effect on masked chafer grubs. Beneficial nematodes can also be purchased but their performance has been sporadic at best.

Small areas of Kentucky bluegrass lawns usually fill-in as conditions warm in spring. Severe damage may require some overseeding. If I have severe damage I usually remove the damages turfgrass and replace it with Kentucky bluegrass sod. If you choose to over seed, remove the dead turfgrass and fill in and level those areas with a layer of top soil or potting mixture. Keep those areas watered to make sure of seed germination.
Have a good lawn!
Floyd McMahon