White Grub Life Cycle & Impact on Your Lawn: How to Get Rid of Them

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Today’s hot topic is white grubs; those white to cream-colored C-shaped pests that cause havoc in your lawn.

White grubs are regarded as one of the most destructive insect pests in residential lawns, partly because they feed below the soil surface and can eliminate the entire root system. 

white grub on lawn

White Grubs Life Cycle

White grubs are the larvae of scarab beetles, which are a diverse family of beetles that includes June beetles and Japanese beetles and are found in every corner of the world.

There are more than 20 species of scarab beetles with white grubs being the most common pests in lawns and gardens. 

Egg Stage

Adult white grubs dig shallow holes in the soil and lay their eggs. White grub eggs can be either pale yellow or brown in color and can have a diameter of up to 3mm in length. 

The shape of white grub eggs is similar to the shape of a sphere and starts off as white but gets darker as they mature.

The white grub egg period lasts between 8 – 10 days and goes through 3 larval stages during their development

Larvae Stage

After the white grub eggs hatch, white grub larvae emerge and start munching on the root system of your turfgrass and plants including potted plants and ornamental plants. 

As the grub’s larvae grow and mature, their feeding becomes more aggressive, resulting in more damage to the grass roots of turfgrass and plants. Brown patches in your lawn are a good sign of grub-feeding damage in your healthy turfgrass lawn. 

The best time to apply chemical preventive treatments is when the larvae are young and located near the surface of the soil, which is generally in the summer and fall. 

Grubs remain as larvae for approximately 11 months, after which they enter the pupae stage

Pupae Stage

The grub pupae stage begins after the grub larvae feeding has finished. The grub larvae then transform into pupae and remain in the soil for 2 to 3 weeks.

This is the right amount of time to transform from pupae to adult beetles. 

The pupae stage of grubs doesn’t last that long, somewhere between 15 to 21 days.

Adult Stage

After the completion of the pupae stage, adult beetles emerge and move up to the top inches of soil. This usually happens in the early summer and lasts for roughly a month. 

Once the grubs move above the soil, they spend between 2 – 3 weeks before mating and laying eggs. The eggs are buried in the soil, and the process repeats itself. 

How Long is the Life Cycle of a Grub? 

There are 4 stages in a white grub’s lifecycle. The time period it takes to reach adulthood depends on the type of grub, but a white grub completes its lifecycle in 76 to 96 days

life cycle of white grub

What Month is Best for Grub Control? 

The best month for grub control depends on whether you want to apply preventative treatments or curative treatments to get rid of the lawn pests already present in your lawn. 

If you’re looking to prevent grubs, it is best to apply grub preventers from April through mid-July when the grub eggs are ready to hatch

Scotts GrubEX1 prevents turf damage when grubs are young and can be easily applied with Scotts spreaders. Further, it prevents grubs for up to 4 months and helps eliminate root damage caused by other crop pests and pest species. 

Deal
Scotts GrubEx1 - Grub Killer for Lawns, Kills White Grubs, Sod...
9,045 Reviews
Scotts GrubEx1 - Grub Killer for Lawns, Kills White Grubs, Sod...
  • One application in the spring or early summer kills and prevents grubs and armyworms for 4 months
  • Helps prevent root damage caused by insects for a stronger lawn
  • Prevents turf damage by killing grubs when they are young

Affiliate links and images pulled from the Amazon Product Advertising API on: 2023-01-30


Check out my full list of recommended grub killers.


For grubs that have already taken over your lawn, the best time to apply a grub killer is when you see the first signs of damage to the lawn roots and turfgrass. 

This is usually when the grub larvae feed the most, which is usually between mid-summer through September. 

After applying grub control pesticides, water your lawn immediately and monitor your yard for grub activity. You probably won’t see immediate results, but can eradication to happen within a few days to a week. 

Identifying White Grub Infestations

There are several telltale signs of a grub infestation, most notably:

3 Signs of Infestation

Key signs of grub infestation in your lawn include yellowing or browning grass, a high number of moths or beetles, and the presence of other pests like raccoons. 

1. Moths or Beetles Flying Around at Grass Level

Although seeing beetles doesn’t indicate a grub problem, it could indicate that one is imminent. Remember, grubs are the larval stage of beetles, which search for healthy lawns to lay their eggs.

And these eggs eventually turn into adult grubs that destroy lawns. If you notice an increasing number of bees and moths in your yard, look out for further signs that grubs may be attacking your turfgrass, or get in touch with your local pest control company. 

2. Increasing Number of Pests in Your Yard 

Pests and animals such as raccoons, birds, and armadillos feed on grubs, therefore may be spending more time in your yard. This is a big problem for two reasons. First, it indicates a grub issue, and second, these animals cause problems of their own. 

3. Brown Patches on Your Lawn 

Brown patches or oddly shaped dead spots can mean that grubs have attacked your lawn. These oddly shaped brown patches usually appear in the late summer or early fall, which is when grubs eat more. 

Take note that brown patches can also be caused by drought or disease, so you’ll first have to confirm that you indeed have a grub problem before exploring administering any grub control treatments. 

brown patch on lawn due to white grubs infestation

Confirming the Presence of White Grubs

The easiest way to confirm the presence of white grubs is by using a shovel to dig up a few small, suspicious parts in your yard

If you see more than 5 grubs per square foot you may have a grub problem. Grubs are only a big problem when they have too large of a population in your yard, but it’s normal to have a few grubs living on a healthy lawn. 

How to Get Rid of White Grubs in Your Lawn?

White Grub Chemical Control

White grub chemical control is only effective if the insecticide reaches the root zone where the grubs are feeding. This can be accomplished by applying roughly 1/2 to 3/4 inches of water after application. 

Repeat irrigation especially for dry soils every 4 to 5 days to continue moving the insecticide into the soil. This step also builds soil moisture and encourages root recovery of the turf. 

If the grubs have made their way deeper into the soil, water up to 1/2 inches before the insecticide application. Doing so will encourage the grubs to move closer to the soil surface and make the insecticide application more effective. 

White Grub Biological Control

White grubs are naturally affected by a wide range of entomopathogens such as fungi, bacteria, and beneficial nematodes. There are several entomopathogenic-based products available for grub control including Bio Green, ORY-X, and Grub X 10G. 


Read my detailed articles on grub control:


man applying grub control pesticide

Prevention of White Grub Infestations

Proper Lawn Care Techniques

As the saying goes “prevention is better than cure”, and the best way to prevent grubs is with proper lawn care techniques and killing the grubs before they hatch

Your lawn should be mowed to the right height and should be properly fertilized for maximum root growth.  

Regular Inspection and Treatment

A few grubs aren’t a reason for concern, but a large population will require an application of a grub control product. Regularly inspecting your lawn is a good practice and will help you treat the grub issue in its initial stages before they become a major issue. 

Maintaining a Diverse Lawn Ecosystem

Another great way to tackle a grub issue is by maintaining a diverse lawn ecosystem, which includes birds like robins and bluejays. To encourage birds to flock to your yard, add bird feeders and birdhouses around your property. 

Maintaining a Diverse Lawn Ecosystem to prevent white grub

FAQs

Q: What Kills Grubs The Fastest?

A: There are two curative treatments that are billed as the fastest grub killers. Carbaryl and trichlorfon kill grubs at all life stages and are great options if grubs are present in high numbers in your yard.

Q: Will Grubs Go Away On Their Own?

A: Grubs will not go away on their own but will hatch in late summer and begin to feed. After the grub eggs hatch, these pests move deeper into the soil to withstand the winter season. 

Q: Do Grubs Return Every Year?

A: If you’ve been treating your lawn for grub damage for successive years, the grubs will not return. But if you have neglected the grub issue, the grub infestation will cause brown and thinning turf, which will gradually increase in size.

Q: How Long Does It Take To Get Rid of Grub Worms?

A: With the right treatment, you can bid adieu to grubs in 10 to 14 days. It may take a bit longer depending on the extent of the infestation. 

Q: Why Do Grubs Keep Coming Back?

A: As mentioned earlier, grubs turn into adult beetles and beetles have a 1 – 3 year lifecycle. So, if you don’t get rid of the grubs, they will keep coming back. 

Q: How Long Does It Take For Grubs To Turn Into Beetles?

A: The answer depends on the type of beetles but some say 30 days while others claim it takes two to three years for grubs to develop into beetles. 


Here is an informative video from Global Life on how to control white grub:

White Grub, Life Cycle & How to control them...?

Final Thoughts

Grubs can cause severe damage when they feed on the roots of your grass. In worse cases, this level of lawn damage by newly hatched grubs and young grubs can’t be fixed, leaving you with only two options – reseeding the area or installing sod. 

Grub populations including annual white grubs go through a 4-stage lifecycle, and the best time to apply control methods is at the beetle larvae stage, which is when the grubs feed most on the grass roots.

Speaking of control of the adult Japanese beetle and June beetle, there are several products available to kill grubs before they lay eggs and cause larval damage such as Scotts grub killer.

Deal
Scotts GrubEx1 - Grub Killer for Lawns, Kills White Grubs, Sod...
9,045 Reviews
Scotts GrubEx1 - Grub Killer for Lawns, Kills White Grubs, Sod...
  • One application in the spring or early summer kills and prevents grubs and armyworms for 4 months
  • Helps prevent root damage caused by insects for a stronger lawn
  • Prevents turf damage by killing grubs when they are young

Affiliate links and images pulled from the Amazon Product Advertising API on: 2023-01-30