See what I mean about conflicting reports on how beneficial these can be? My compost pile has definitely been untended. I saw the grubs when I first turned it after a winter of leaving it alone. Here a post saying that the grubs are beneficial: http://faq.gardenweb.com/faq/lists/soil/2002013027009234.html Here's another one on the exact same grub, saying that they can be very destructive to your lawn: http://en.wikipedia.org/wiki/Green_fruit_beetle And Soldier fly larva are pretty much acclaimed for being helpful, so we should be careful lumping everything into a single category. http://extension.oregonstate.edu/news/story.php?S_No=802&storyType=garde I was hoping for a solid ID on what kind of grubs I had in my compost, but my pictures may be too fuzzy for anyone to tell for sure. Here is a link that might be useful: Soldier Fly Larvae

My roses did very well for a few months after I planted them this past spring. They slowly declined almost to death by July. Just yesterday, I realized one was not going to make it so I pulled it out. While turning the soil in the hole there were at least 20 grubs!! Now of course, I'm wondering if that was the reason they were doing so poorly. I am from Long Island and never had a problem growing anything and had beautiful roses, so I am new to growing anything in Az.I have used DE in my garden for ants, but I am wondering if I should add DE to the soil now, as I was planning on putting new rose bushes in the same holes before I found the grubs. Any solutions or advice will be welcomed. Thanks

I notice that this thread started in July last year but has some current discussion. I think that curl grubs can do a lot of damage; more than many people suspect. The grubs are underground, out of sight and probably responsible for a lot of fatalaties that are blamed on other causes. Right now I have veronicas and penstemons that I can just lift off the ground because they have no roots; all eaten away by curl grubs. A little dig in the soil underneath will usually find a few fat grubs that can be chucked to the birds. A biologically safe and efficient way of getting rid of them is to use nematodes that you can buy through some nurseries. On a larger scale, councils spray nematodes on sports grounds, garden parks, etc. Black flower wasps also hunt them; they are fairly big wasps, with black bodies and metallic-blue wings. I have seen them burrowing into the soil, using some kind of natural ability to home in on the grubs.

Thank you, Stephanie, for the tip of Garden Tutor Soil pH Test kit strips. I find that soil pH test via a solution (red-cabbage juice) is more accurate since it takes at least 1/2 hour for the minerals in soil to dissolve in water. I tested soaking coffee ground in red-cabbage juice, at first it was acidic (pinkish), but after 1/2 hour soak, the solution became clear, coffee ground is known as a buffer. Same with rose park nearby, they scattered a layer of gypsum on top of their clay. I scoop up 1 heaping Tablespoon of their soil and tested in red cabbage juice. At first the solution turned pinkish (acidic), from the 18% of sulfur dissolved first. After 1 hour, the solution became very blue (alkaline), from the calcium of gypsum being slowest to dissolve, plus the alkaline minerals in soil was slow to dissolve. SARENA: for the reason above, it's best to mix gypsum 1 month in advance into soil, and let rain or a few waterings release its acidic sulfur to dissolve minerals in soil (rather than to corrode roots). Since you are in a high-rain climate, it's good to have solid minerals on top to buffer acidic rain, such as a thick layer of Worm Casting (pH 7.4), or your clay (if alkaline like mine at pH 7.7). Vermiculite is to improve moisture and to hold nutrients, plus to make potting soil fluffy for wimpy own-roots. Perlite has zero nutrients but good to MIX-IN so roots can have more oxygen for growth. Own-root roses like moist but airy soil. Both vermiculite and perlite is best mixed into potting soil. One rooting method recommended by University of CA at Davis is to mix 1/2 vermiculite (for moisture & cation exchange) plus 1/2 perlite (for aeration).