The Dirt

Best Treatment for Grubs in Your Lawn and When To Apply It

Written by Senske Services | October 14, 2025 at 7:39 PM

Grubs are among the most destructive pests your lawn can face. They work silently underground, chewing away at the roots of your grass until large sections of turf turn brown and die. 

Beetle species and grub activity vary by season and region, which means when and how you treat your lawn makes all the difference. That’s why homeowners across the Western U.S. trust Senske. With decades of local experience, we know how to align grub control strategies with your region’s growing conditions and beetle activity. 

In this guide, we share how to identify these lawn pests, the best treatment for grubs in lawn turf, and the best time to treat for grubs in Washington, Idaho, Utah, and Colorado.

Understanding Lawn Grubs

Grubs are the larvae of beetles like June bugs, masked chafers, and Japanese beetles. These small, white, C-shaped pests live just below the soil’s surface and feed aggressively on the roots of your lawn. 

A grub’s life cycle spans about one year and includes four main stages:

  1. Egg: Adult beetles lay eggs in the soil during summer, usually between June and August.
  2. Larva: Eggs hatch into grubs, which feed heavily on grass roots in late summer and fall. This is the most destructive phase.
  3. Pupa: In fall and winter, grubs move deeper underground and enter a resting stage as they transform into adults.
  4. Adult: Mature beetles emerge from the soil in late spring to early summer and begin the cycle again by mating and laying eggs.

Knowing when to apply grub control starts with understanding this lifecycle. Treatments are most effective during the larval stage, when grubs are actively feeding and still close to the surface.

Best Treatment for Grubs in Lawn

Not all grub treatments are equal, and using the wrong type at the wrong time can leave your lawn vulnerable. Let’s break down the two primary types. 

Preventative Grub Control 


Preventive grub control is a proactive approach using insecticides like imidacloprid or chlorantraniliprole. These solutions are absorbed into the grass and ingested by grubs as they hatch and begin feeding.

The ideal window for this method is late spring to early summer, before grubs emerge. When applied properly, this is often the best treatment for grubs in lawn grass because it reduces the chance of infestation.

Curative Grub Control


If your lawn already shows signs of damage, such as patchy, loose turf or animal digging, you’re in curative territory. Products like Dylox (trichlorfon) kill grubs on contact and offer fast-acting relief when timed right. 

Curative treatments are best applied in late summer to early fall, when grubs are still close to the surface and actively feeding. Once they burrow deep for winter, treatment becomes ineffective. 

Professional vs. DIY Application

While DIY products are available, they often lack the potency and precision of professional applications. Senske technicians apply insecticides based on real-time soil temperatures and local grub activity, ensuring optimal timing.

Mild cases may be manageable with store-bought products. However, for full-yard infestations or recurring issues, professional lawn grub control is necessary for lasting, reliable results. 

Best Time To Treat for Grubs by Region

Local conditions affect when grubs hatch and feed. Treatment timing should match your region’s specific patterns for the best results. Here’s what that looks like: 

 

Washington (Spokane, Tri-Cities, Kennewick)

  • Common Pests: European chafers, billbugs
  • Best Time: Preventative treatments in late May to early June

Spring in Washington often brings wet soil conditions, which make early treatment more effective. Apply preventative products in late May to protect against early egg-laying by beetles. Keep an eye out for turf damage in July and August, as this could signal a need for curative action.

Idaho (Boise, Meridian, Idaho Falls)

  • Common Pests: May/June beetles, masked chafers
  • Best Time: Preventive in May-June; curative in August if damage appears

Idaho’s climate creates a spike in grub activity during the hot, dry midsummer. Begin monitoring turf in early summer for thinning or brown patches. 

 

Utah (Salt Lake City, Ogden, Provo)

  • Common Pests: Japanese beetles, masked chafers, June beetles 
  • Best Time: Start preventative treatments in June; monitor through August

Utah’s high temperatures and widespread irrigation create perfect conditions for grub outbreaks. Lawn care plans should include pest control alongside fertilization. Preventive applications in June are best, but remain alert to signs of stress and apply curative treatments if needed.

 

Colorado (Denver, Aurora, Broomfield)

  • Common Pests: Japanese beetles
  • Best Time: Apply preventatives in May-June, especially in lower elevations 

Japanese beetle populations are increasing across Colorado, especially in warmer, low-elevation areas. In these zones, early preventative treatment is essential. In contrast, grub activity starts later at higher altitudes, so treatments may be delayed until late June or early July. 

Why Professional Grub Control Is More Effective

Knowing when to treat is one thing; executing it precisely is another. Professionals combine timing with the right product, dosage, and method to match your lawn’s conditions.

At Senske, our technicians use real-time cues like turf stress and insect activity to guide each treatment. This timed approach ensures applications hit the right stage of the grub lifecycle. 

DIY efforts often miss this mark. Store-bought products are more limited in coverage and effectiveness. In contrast, professional-grade solutions work faster and reach deeper. They’re designed to target grubs without harming the rest of your lawn. 

Ultimately, lawn grub control doesn’t work in isolation. Proper watering, fertilization, and aeration are also required to boost overall lawn health and resilience.  

How Senske’s Grub Treatment Program Works

Senske’s lawn grub control program is built around local expertise and careful timing. We don’t offer one-size-fits-all solutions. Instead, each program is customized to match your region’s beetle activity, soil conditions, and seasonal patterns. 

Here’s what you can expect:

  • Inspection and grub risk assessment to identify signs of damage or potential infestation
  • Customized treatment schedules by region, timed to target grubs at their most active stage
  • Use of EPA-approved products that are safe for pets and families, but effective against grubs
  • Options for preventive or curative treatments, based on your lawn’s health and history

Our team applies each treatment with care, using professional equipment and techniques that improve coverage and results.

DIY Grub Treatment Mistakes To Avoid

Grub control might seem simple, but minor missteps can lead to wasted time, money, and even more lawn damage.

Be aware of these common mistakes: 

  • Treating too early or too late, when grubs aren’t active near the surface, makes products far less effective.
  • Using insecticides not labeled for grubs can result in poor results and unnecessary chemical exposure.
  • Skipping follow-up applications, especially after rainfall, reduces control and allows grubs to survive.
  • Overwatering or mowing too short weakens your lawn, making it more vulnerable to grub damage.
  • Misdiagnosing turf issues like drought stress or fungal infections can delay proper treatment.

A professional inspection from Senske can help you avoid these errors by creating a plan that targets the real problem at the right time.

Stop Lawn Damage Before It Starts With Senske

The best treatment for grubs in lawn turf depends on the stage of the grub’s life cycle and how active they are in your area. Timing is everything, and that timing isn’t the same in Spokane, Boise, Salt Lake City, or Denver.

That’s why regional insight matters. Soil temperatures, beetle species, and lawn conditions vary across the western U.S. As a local team, Senske understands these patterns and applies treatments when they’ll work best. We offer preventative and curative solutions that fit your lawn’s needs and the season. 

Get ahead of the damage. Schedule your Senske lawn inspection today and let our experts build a plan that protects your lawn from the ground up.