Will birds eat these grubs? If so put out an advertising sign for the birds :) By ad sign I mean a bird bath (or just a shallow dish with water) and maybe a little bird seed to get the birds moving into the area.

Otherwise tilling should do a number on the grubs.

You don't want to till adjacent to the fruit trees - it will damage the fine feeder surface roots. Raking out the compost to expose the grubs may be advisible. The birds should then take care of much of the problem. And pick the fruit before it becomes fully ripe - the beetles are attracted to over-ripe or bruised or damaged fruit. Or trap them (directions follow).

Mulching to a depth of 2-3 inches is usually sufficient to retard weed growth and conserve soil moisture. Less will be ineffective and much more is a waste.

Here is a link that might be useful: managing fruit beetles

You don't want to till adjacent to the fruit trees - it will damage the fine feeder surface roots.

Good point, I didn't catch that.

I was planning to shovel the compost away from my fruit trees before I rototilled it. I may do that and then replace it with some fresh compost that doesn't have any beetle grubs in it. Of course next year I will have the same problem.
It is too late for me, since I already planted my Goldmine and Snow Queen Nectarines, but for anyone In southern California plagued by Green Fruit Beetles I would recommend planting Arctic Star Nectarines. They ripen their fruit very early, before the fruit beetles emerge enmasse.

You might want to try some garden grade Diametacius Earth (forgive the spelling". That does a great job on slugs by cutting them open and making them bleed out. It's also pretty cheap.

Ron
The Garden Guy
http://www.TheGardenGuy.org
"New Article & Journam Entry for Feb."

Ron, the grubs are under six to eight inches of compost. Assuming I am supposed to sprinkle the diatomaceous earth on top of the compost, wouldn't the grubs have to come up to the surface and crawl through it? I don't think they will come to the surface until they emerge as adult beetles. BTW, that link to the website about green fruit beetles says compost containing manure, which I have, is the favorite place for these beetles to lay their eggs.

Not at all Californin,
The DE will migrate through the mulch as it rains. I usually have a good 4-5 inches of mulch, and it goes right through and kills the slugs every time.
I don't know much about those specific grubs and suspect they are specific to your neck of the woods, but I would assume the DE would have the same effect. It would be worth a test on at least one area just to find out.

Ron
The Garden Guy
http://www.TheGardenGuy.org
"New Article & Journam Entry for Feb."

Is this a grub that can be controlled with benefical nematodes? I have no idea how much that would cost for your square footage. Or maybe you should get the same natural control method that I have - families of skunks coming into your yard, tearing into the topsoil, clearcutting all of your seedlings, and occasionally gassing you out for no good reason at 3 am. :)

If you are not an expert in fruit beetle grubs, I suggest you find one to verify the identity of your grubs. I don't live in a fruit area, and my compost is full of grubs that I cannot identify. Not all beetles are bad. Some are necessary to survival.

I've always believed in letting natural processes work for me. If this were my situation I would look at it from this point of view. I would imagine that the beetles would have laid their eggs somewhere even if you hadn't provided the manure. However I think you may have a good situation on your hands and don't even realize it. Most likely the increased concentration of beetles, will lead to an increase in predator populations shortly. Anything you do to control the beetles will most likely harm these beneficials as well. It would make more sense to me to let them be and let the predators do the work for you. Then after the beetles are gone you will have a bunch of hungry predators lingering around your trees. Not a bad situation after all.