Grubs, skunks and moles -- oh my!

By John Fulton

[October 06, 2009]  Unlike lions, tigers and bears, the grubs, skunks and moles are not make-believe, and they can really cause some damage to your lawn.

Let's start with the grubs, since most of the problems are associated with them. We are faced with a few different types of grubs, with the Japanese beetle larvae and the June bug larvae being the most common. These also are the grub types most damaging to your lawn.

Starting with the adult beetles, the life cycle goes something like this. The beetles mate and lay eggs in a lush, grassy area. The egg then hatches into a small grub. The grub overwinters in that stage, diving deeper into the ground as temperatures cool. In the spring the grub comes back to the surface as temperatures warm. After a few weeks to a month, the grub will go into the pupa stage. Then the adult emerges from the pupa in May or June to start the cycle all over again.

It normally takes in the range of 10-12 grubs per square foot to cause damage to decent turf, and with the good growing conditions we have had this year, that number can almost double. This means we probably won't see much actual grub damage unless we have a sudden drought. The other thing is that the grubs will begin to go deeper in the soil as temperatures cool. Most of the damage is coming from four-legged critters seeking the grubs as a food source.

Moles traditionally eat grubs and earthworms. Moles have a long, straight, shallow tunnel they use and then several short, curving tunnels branching off where they have sought food.

Skunks will actually dig individual holes to get grubs. Skunks have a wonderful sense of smell and tend to work in a specific area. The holes they make are usually about the size of a penny, and they go as deep as the grub was (usually less than an inch and a half).

As for your control options, that gets more difficult this time of year. A month ago, the best approach would have been to apply a grub control treatment. But we are approaching the time when the grubs will go deeper into the ground, so the benefits of a grub control treatment will be minimal. If the problem is grubs, you are probably out of luck for this year. Grub controls are best applied in August or September to control the small ones. If the problem is the animals eating the grubs, you are going to be reduced to individual elimination.

Mole control is best accomplished by trap or poison baits. There are three main types of traps: the jaw type, the plunger type and the loop type. The plunger type is probably least effective, since it is hardest to get set to the proper depth. The folk remedy controls usually involve bubble gum or Juicy Fruit gum in the runs, but these don't work consistently enough to recommend them. You're better off chewing the gum yourself while you are setting the traps. There are also poison baits available that are effective. The soft baits, which are meant to imitate grubs or worms, are effective. Poison peanuts or milo are not, since moles don't eat seeds.

Skunk control is another ballgame. There are state trapping regulations covering skunks, so you are best to check those out yourself. There is no season on shooting skunks, if that is an option where you live. The best control in this case is really your defense, and that means reducing the grub population where you don't want the digging occurring. Of course, there may just be a 10-foot move to another area where grubs are available.

[By JOHN FULTON, University of Illinois Extension, Logan County]