I think they are the larval stage of an inch-longish black June beetle. Robins love them, and crows redeem themselves by harvesting them agressively. They are hard on emerging beans and young plants of any kind, emerge in the evening to feed, and retreat by daylight. They can often be found by scraping around the corpses of their victims just underground. They dislike sand and wood ash and are easily controlled with common insecticides. Little bast'ds took out half my green beans this year. Here is a link that might be useful: June beetle larvae

You said you have apples in your yard? A beetle could have laid eggs in your yard because of the apple tree, knowing that when the grubs pupated into beetles, they'd have a food source right there. Did you say you spread compost over your yard? It could have been that a beetle egg was in the compost, and it hatched after the compost had been spread in your yard. Or if you have a garden that you put compost in, or do lasagna gardening, the grub could have crawled over from that area. I found a big fat one where I had piled up lots of organic matter to decompose over the winter so I could plant some roses in the spring. The fruit beetle isn't the only beetle that produces huge grubs that eat decomposing materials, so it could also be one of the other ones. The thing that really distinguishes these grubs from lawn grubs is the size. Lawn grubs are fairly small compared to the big fat composting type grubs. Deanna

If you have the number you suggest why not go for direct assault on them. Spray your lawn with diazinon or Solgard ...et al. The grubs are feeding now from the eggs that were produced last June and now the full grown beetles are eating their way through lawns and will, in a short time, stop eating and dig their way down into the soil to spend the winter. They then return in the spring to take up where they left off. We've got 'snowbirds', now we have 'snowbugs'. Its too late for nemotodes to work effectively--probably cant find them anyway...they are a living organisms. Best time for this attack is July/August/September when the grubs are close to the surface. Heck, if you can see them, you can pick them up and drop into a soapy solution. Or spray with the insecticide. The next best time is in early spring when the grubs are once again near the surface; having come up from their winter quarters. They are probably too larger than when they went south. You might too, next spring, look for any parasites that feed on grubs. Wasps....they wont sting you, if you see them hovering over the soil surface are probably looking for grubs. Ground beetles and ants can also be helpful in controlling grubs. A good lush, healthy lawn is still one of the best defenses against invading grubs. Watered regularly, fertilzied regularly, cut at the proper height and leaving the clippings on the lawn can make for a great looking lawn. Good water retention in the fall can also make for a stronger turf to go into winter. Early snow-melt with rain can often make it better for lawns in spring.

Saying a grub is white is kind of like saying the sky is blue. Post a picture, and I'll give it a whirl. Two or more pictures would be better, one showing the overall appearance, one showing a sideshot of the head as closeup (in focus) as you can get it, and another showing the pattern you noticed. Oh, a shot of the underside would be helpful, too.