The grubs are the larval stage of Japanese beetles and/or June bugs. They remain underground until they emerge from the ground in the spring. So yes, they are still in the ground for a few more days to weeks. These grubs are your skunk problem but not your grass problem. Your problem this summer will the be the grubs produced by this year's crop of beetles. Spraying the current grubs will do nothing against this summer's grubs...although it might chase the skunks away for now, which is what you really want. You can check for grubs in your lawn in June. Dig up 1 square foot of lawn and count the grubs. If you have more than 12, then you have a problem and should treat for them. If you have fewer than 12, you probably won't notice any grub damage.

Sod webworms are caterpillars. You can control them naturally by allowing wasp nests to form under your eaves. These "paper wasps" create nests that are like paper. Inside each cell of the nest they lay an egg and insert a paralyzed caterpillar for the newborn larva to eat. These wasps are magical creatures. As long as you leave them alone, they will quickly learn who you are and your habits and leave you alone. This can take a lot of conditioning on your part so you don't dance around waving your arms when they approach you. Last summer I had a wasp population of about 300 all around my house. They all knew my routine so I could take amazingly close up pictures like this without them paying any attention. That was from about 1.5 inches away, so they really will leave you completely alone. And they will clear your property of all caterpillars. As for grubs, it has been reported that they rarely strike the same neighborhood two years in a row. The time to watch for them is after you notice beetles swarming your porch lights. Make a note of when that is and, about a month later, inspect your lawn. Dig up a full square foot of soil about 2 inches deep. If you find more than a dozen grubs, then you have a problem. Normal lawns should tolerate a dozen grubs per square foot. If you have fewer than that, you should be good for the rest of the year because some will not survive. If you have more, then spray away.

The time to apply grub control is about 4-6 weeks after you see Japanese beetles or June bugs swarming your porch lights. If you don't have the parents, then you can't get the grubs. Don't just apply because you have not had grubs in many years. I've never had them and never used insecticide. Before you apply check to see that you have the critical mass of grubs. Your yard can handle up to about 12 grubs per square foot without you even noticing them. If you find more than that then you can start to get excited about them. They are a summer time issue. If you don't do anything about them all summer, then you don't have to do anything for the rest of the year, because they stop feeding.

Grubs are only a problem following a heavy accumulation of beetles around your porch lights in the late spring. The old timers say if you see them one year you will not see them again next year. Don't know why. I use beneficial nematodes for grub control but only after the heavy beetle populations are seen. Before you do anything you should dig around looking for them. If you find more than 12 per square foot, then apply something. Otherwise your soil should tolerate them. Beneficial nematodes bring a disease to the grubs which kills them in 24-48 hours.