Control white grubs

Aside from beneficial nematodes, what else can be done naturally to control white grubs (video) in your lawn?

Problem Identification

When you dig and find large white grubs in the soil, you might have a problem. If you find 10 grubs in a shovel-full of dirt, then you have a problem. If you only find an occasional grub, then your lawn is not suffering from an infestation. If you see birds, moles, raccoons, or skunks feeding on the grubs, then it's a safe bet that you have a problem. The smaller (immature) the grub, the better it is for controlling them.

Lifecycle

It's important to know the lifecycle of the grub so that you can time treatments effectively. See http://www.nysipm.cornell.edu/publications/grubs/life.asp

The best time to kill grubs is when they are young. When you see the beetles flying around in August, you'll probably notice them aggregating to reproduce. That means the females are laying eggs in the lawn. That is the best time to treat because as the eggs hatch, the young larvae eat close to the surface and will be ingesting the bacteria which will in turn grown and kill the grubs when they are most vulnerable. By late October, the grubs have burrowed deeper to over-winter dormant. In the spring, as the ground warms, the grubs will come back toward the surface and begin feeding again. But by now they are in their 3rd or 4th instar so it will take longer to kill them and the larger grubs will do more damage compared to 1st instar nymphs.

Killing Beetles

You'll find mature beetles flying into your lawn, attracted by flowers, or other beetles. Drop the beetles into a bucket of soapy water.

Milky Spore (Paenibacillus popilliae)

wp:Milky spore is a bacteria that will control Japanese beetle grubs. The bad news is that it's not too effective for other types of grubs. Furthermore, in New England, due to cooler soil temperatures, milky spore disease has not been very successful in controlling white grubs. Where it does work, milky spore takes 3-5 years to really establish itself in your lawn for full protection from Japanese beetle grubs. The good news is that the bacteria is pretty much permanent (lasting 15 years or more). In contrast, beneficial nematodes act very quickly (in days), even on large grubs. But, the nematodes will die off when either their food source is gone (no more grubs, Yay!) or the winter temperatures kill them. So nematodes are a quick, but temporary fix while milky spore is a slow, but permanent fix. Obviously it would make sense to use both in tandem in the beginning if you're starting with a moderate to severe grub problem.

Purchase

Arbico Organics

Beauveria bassiana

wp:Beauveria is a fungi which can be an insect pathogen. Cost is ~$120/acre. I've seen multiple references to using it to fight bed bugs too. Here is a quote from a researcher:

That's an important distinction of natural pest control and organic farming compared with artificial chemical methods. Of course there are lot's of people with a vested interest in artificial methods, which can make it hard to get good facts.

Purchase

http://www.arbico-organics.com/product/mycotrol-beauveria-bassiana-organic-insecticide/organic-insecticides

Metarhizium

Presently, researchers are investigating the effectiveness of the fungal pathogen Metarhizium on the mortality of several species of white grub larva. However, more research is needed to determine the effectiveness of this fungus as a control method for white grubs.