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Grub Damage; How To Repair Your Lawn

As most people in the Eastern and North Eastern Counties of Luzerne, Lackawanna, Monroe, Bucks, and Montgomery know, grubs are a frequent and often severe problem in Pennsylvania lawns. In Pennsylvania, these grubs are most often the larva of Japanese beetles or Northern masked chafer grubs. Affected gardens become spongy in patches as their roots are gnawed away, and layers of sod can be easily peeled away. The most visible signs of grub damage are patches of dead or dying grass that crop up in early summer or fall. The most extensive grub damage in Pennsylvania lawns takes place between May and June, which is also the best time to treat a lawn for grubs.

Lawn Grub Cycle


Residents and business owners have seen a lot of grub damage this past fall in the Eastern and Northeastern Pennsylvania areas. Green Machine, who have over 37 years of experience treating lawns in Lackawanna, Monroe, Bucks, Montgomery Counties suggest addressing this damage early. If it is not resolved soon, the pre-emergent crabgrass control that’s typically applied in the spring will inhibit the growth of new seed in the damaged areas. Also, without crabgrass control, lawns will have the crabgrass take over choking out all of the newly planted turfs.

If you are seeing patches of grass turning brown and the area is ever-widening, Japanese beetle grubs may be at work.


When the injury is severe, the grass can be lifted readily and almost rolled back like a carpet – and the grub worms may be seen underneath at the outer rim of the brown patches, where the grass is still green.

These grubs feed on grass roots cutting them 1 to 2 inches below the soil surface. This type of injury is most likely to occur during late summer, particularly in August and September and in mid to late spring. Newly damaged grass wilts quickly on hot days. In some cases, a quick, thorough watering will enable the soil or turf to reroot and to survive.

Lawn Grub Control & Treatment

Once you detect  Japanese beetle grubs, your method of attack is to use an insecticide. 


Today, you have a choice of several excellent products to use to prevent grub infestations and damage. They include chlorantraniliproe (Acelepryn), clothianidin (Arena), imidacloprid (Merit), halofenozide (MACH2) and thiamethoxam (Meridian).

But not all lawns suffer from grubs, at least not in sufficient numbers to cause noticeable lawn damage. While some lawns are historically more prone to grub damage than others (and clients’ are glad to pay for a preventative chemical application), infestations that result in lawn damage in many cases can be unpredictable and sporadic. They can also be severe, killing large sections of Eastern and Northeastern, PA lawns.

When to Treat for Grubs?

This first-instar stage is the best time for curative control of grubs. The longer that grubs are allowed to feed, the larger they become, the more lawn damage they do and the more difficult they become to kill.

**From first-instar grubs, they molt (shed their skins) and emerge as larger second-instar larvae within several weeks. As they grow, their appetites increase. They molt again in late summer or early fall to become larger, more robust third-instar grubs. At this stage of their development regardless of the product you select and use, grubs are very difficult to control. Green Machine Lawn Care suggests contacting a local lawn care professional to appropriately correct grub damage and rid your lawn of future infestations.

How To Prevent Grubs For A Healthy Lawn?*

  1. Do Not Mow Your Lawn
    In order for the grubs to get into the ground in the first place, the beetles need to lay its eggs. As it turns out, they don’t like to do that in long grass.

Lawn grubs don’t like to lay eggs in the long grass!

You can cut your grass of course, but keeping it relatively long can help you prevent the insects to look at your property as an incubator. There are other ways of keeping the little lawn pests away, like:

  1. Over-Seeding Your Lawn
    Over-seeding by spring and early fall are much healthier than overeating, and in this case, it can be extremely beneficial for the general health of your lawn. Again, grubs aren’t just a problem; they attract problem.

When these pests eat your plants’ roots only to end up as the food of an animal that will do equally big damage to your garden, well, that’s pretty much the worst case scenario as far as grub infestations go.

By over-seeding your lawn during the spring and early fall, the grass will merely be too dense and thick for the beetles to find it accommodating.

  1. Fertilizing Your Lawn A Valuable Ally
    When it comes to insect-related plant problems, fertilization can be a precious ally. People tend to fear this process these days, but in reality, it is still the most potent weapon against specific pests.
    The fertilization process itself should be done in two phases for maximal efficiency, the first phase during the fall months, and the second phase of the early spring lawn care season.

If possible, putting down a layer of dead leaves [leaf mulching] after the first phase is ideal, that way you will maximize the fertilizer’s effect during the winter months.

  1. Water The Lawn Is Not Always Good
    Lawn grub eggs have a dirty little secret, without enough water, they cannot hatch.

While it’s true that your lawn needs to be frequently watered during the hottest months, and coincidentally the grub eggs hatch around the same time (early August), you can circumvent this problem by changing your watering schedule.

See, your lawn is utterly beautiful with getting a lot of water once, instead of you spanning your watering activities over several days.

If the eggs do not get constant moisture, their chances of ever hatching will reduce significantly.

  1. Applying A Beetle Grub Poison
    Fertilization can help you prevent the problem while poisoning is a measure of the times when you realize that the grub eggs have already been laid down.

Certain garden chemicals contain potent – but to humans not dangerous – chemicals, like imidacloprid or halofenozide.

Merit insecticide [amazon] is a product like that, and it will poison the grubs when they hatch. Make sure to educate yourself about the product though, as some can affect (or even kill) the birds that would eat the grubs.

Penn State University also suggest using neem oil – “Another alternative is neem oil, a botanical pesticide. Neem tree oil contains insecticidal properties and can act as a repellent, deterring feeding, insect growth and egg laying. Mix the neem oil with water as directed on the label and spray the diluted solution generously on affected areas.”

  1. Wasp attack
    Despite their reputation, parasitic wasps can be beneficial insects for more than one reasons. Certain types (ground hornets, which are wasps) hunt grubs and will, in fact, seek them out to take care of the problem for you.

Okay, they’ll be more driven by their predatory instincts than your wishes and hopes, but it’s the result what counts, right?

  1. Attract Birds To Eat Lawn Grubs
    Another counterattack comes from Mother Nature herself, birds. Yes, birds can cause quite a ruckus themselves, but overall they are still beneficial to your garden.

You should take measures to protect your seeds from them, but they will also snack on the grubs which are ultimately something we want.

How can you attract birds to your garden? It is easy. Just put up a bird feeder close to the problematic areas, and let them go to town on it.

Putting up a bird feeder may be a more of a “solution” that is not very dependable and would be low on my list of remedies!

  1. Kill Grubs In Your Lawn With Beer
    Yes, it’s not just you who’s likely quite fond of beer (sorry if I’m way off), but these slimy little lawn enemies as well. This idea may sound like a waste of a delicious beverage, but you don’t have to use the best stuff, they aren’t picky about it.
    Just dig a hole big enough to accommodate a plastic container of your selection (it shouldn’t be too big or too high), and pour the stuff in it. After that, all you have to do is wait until the morning.

You may also collect a bunch of slugs and snails. Using beer may be possible in a small area but a large lawn just not very practical.

  1. Apply Parasitic Nematodes To Your Yard
    Sounds frightening, but parasitic nematodes [amazon] will mostly affect the grubs, though not all types.

Beneficial Nematodes are an organic and most efficient way to battle soil pest.

-Kills Over 200 different species of soil dwelling and wood boring insects.
-Easy to apply and Harmless to humans and pets.

10 million Nematodes are enough for the preventative control of soil-dwelling insects in approx. 2,000 – 3,000 sq.ft of the soil surface area.
For best results or high infestations. Multiple releases are recommended.

Some species of white grubs will be more susceptible to the method than others, but they work excellently against the most widespread type (Japanese beetles).

If you are having issues with grub damage on your lawn, contact Green Machine Lawn Care today to request your free lawn analysis and estimate.



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