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I've got some white grub damaged areas (I've seen some on the top of the damaged areas) in our front lawn that will need to be replaced. It's probably too late in the cycle to really do anything about the grubs now, correct? What steps can/should I do before I get my exercise and start laying some new St. Augustine sod (which will probably have to be done over a few weekends)?

Stormy, last spring I applied an insecticide (a "once a year" kind, but I don't remember the brand though) when I saw some grubs on the neighbor's grass (probably ended up being the wrong time of year... should have been here sooner about it).

I'll upload a photo when I have some time, but they look like the "C"-shaped grubs found when you Google "lawn grubs"

Sorry for the delay... pneumonia is a bear... here's a closeup of the lawn damage. There are several patches like this, the whole area affected is about 27' x 20', but I won;t have time to do that all at once... gonna try to find some grubs today

Lawn Damage http://www.unkfrank.com/images/StackExchange/LawnCloseup030715.jpg

Over the weekend, I tried dumping several 2 gallon buckets of soapy water onto some areas of the damaged lawn, but I didn't see any grubs come to the surface during a few hours of checking.

  • What if anything have you already tried for control of grubs? Grubs, larvae are usually kept below damaging numbers by beneficials in the soil, voles, gophers and birds. Have you ever used a non-specific insecticide on your lawn? – stormy Feb 26 '15 at 19:49
  • Thanks for replying! Applying pesticides to your lawn is what set you up for damage by grubs. Your goal is to get a healthy microbial, micro and macro organism community in your lawn's soil. Grubs are normal, just don't kill your beneficials that keep grubs from killing your lawn. If your soil is healthy, your lawn will be able to be healthy. Pesticides are nothing more than a 'bandaid' to problems that could be prevented...how does your lawn look now? – stormy Mar 3 '15 at 20:06
  • Let us do the work to identify the grub...critical step!! Please send pictures and you might get even more personalized answers! It is expensive if you don't know what is causing problems and you 'try' different products without really knowing WHAT your problem IS. Look up all the lawn stuff on this site...become an expert on lawns! Don't need help from chemicals if you learn about your grass and how to keep it healthy. – stormy Mar 3 '15 at 20:15
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I wouldn't apply any pesticide for the grubs! I'd take a bucket of soapy water, dump it on a spot in your lawn's soil. If a lot grubs come up for air (there is a threshold that needs to be determined as well as exactly what kind of grub you are dealing with)

Once you know if you indeed still have a problem and what your critter is, I'd use a sod cutter, remove the sod using it if possible to make planting beds by mounding up the turned over sod sections, then covering with 2-4" topsoil and allow to decompose. Great stuff to make planting beds with or just give it away or pay to dump the sod.

I'd then take a power rake or dozer to dig up your existing soil, water, allow grubs to be eaten by birds or mature and fly away. They won't hurt your trees, shrubs or perennials. They love the crowns and roots of your lawn. We'd know better once the grub is identified of course!

Allow to dry, grade, rake and roll. Use an organic fertilizer with bacteria and mychorrhizae. Use a spreader, don't throw by hand. Then lay your sod. If you use any pesticide make sure it is SPECIFIC to whatever grub/insect you need to control. A non-specific pesticide will kill everything including the beneficial nematodes and other beneficial soil life that is responsible for keeping grass-eating grubs in check. The only lawns I've seen (in the Pacific Northwest) that were decimated by grubs were lawns that were treated with a non-specific pesticide that killed beneficials that keep insects such as your grubs from ever becoming a problem. Not that familiar with St. Augustine but the principle must be the same. Without more information I am just giving you my experience and guessing. (Ouch)!

Please send pictures of the grubs for identification. Also, pictures of your lawn that shows the damage. How large is your lawn? Then we'll be able to be responsibly answering your question. Also, when you do the soapy water test, approximately how many grubs come up within a square foot? For best results, try to get a soil test (go through your extension service for little or no cost).

  • Soap is usually used at a hugely higher rate (concentration in the water) than pesticides, and so even though it's safer in itself (lower toxicity rating), it can be more toxic to the environment than pesticides, in normal quantities. Really depends on the soap, though. – J. Musser Feb 26 '15 at 22:04
  • The soapy water is just to figure out how many grubs per sq. ft. Not for the entire lawn. The threshold is way higher than I thought to indicate a problem. Just need more information from OP. – stormy Feb 26 '15 at 22:29
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Where you are, your grubs (most likely masked chafer), are probably full-size by now, and hanging out down lower than you can efficiently control. I'd wait until April, where (in your area) the larvae will move to the surface, pupate, and fly til near the end of June. Then they'll lay eggs, which will hatch into new larvae. This period (when the pupating/hatching grubs are near the surface) is the best window of control.

This beetle has 2 flights (generations) a year in your area, and the second one will happen in August/September.

So I'd wait until April, control the grubs (one application) and then lay the sod. Of course, it'll be warmer out by then, and you'll have to water, but it won't be as bad as summer yet. See my answer here for more details on control:

If you test for grubs later in the season, and come up positive, you can do another application.

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