Beetle Activity Alert: Grub Season Is Underway in the Northeast  

Throughout July and into August, beetles are actively flying and laying eggs across the Northeast. These beetles are the adult stage of white grubs, one of the most damaging lawn pests in New England. When grub feeding is combined with summer drought stress, significant turf damage can occur.

Understanding which beetles are active now—and knowing when to scout for grubs later this summer—can help prevent costly lawn repairs.

Common Beetles to Watch For  

The following beetle species are among the most common grub-producing pests in the Northeast:

European Chafer  

A major turf pest in New Hampshire and eastern Massachusetts. European chafer adults are nocturnal, so they often go unnoticed while laying eggs.

Japanese Beetle  

Although populations appear to be declining in some areas, Japanese beetles remain widespread throughout New England and continue to be a major concern for lawn managers.

Asiatic Garden Beetle  

Common throughout southern New England, Asiatic Garden Beetles are particularly found in lawns and garden beds.

Oriental Beetle  

Frequently found in coastal regions and often active during the evening hours.

When to Scout for White Grubs  

The best time to scout for white grubs is from late August through mid-September.

Keep in mind that prolonged dry weather as we have experienced this year can delay beetle egg-laying and grub development, so timing may need to be adjusted based on local conditions.

How to Check for Grubs in Your Lawn  

1. Cut a three-sided square in the turf approximately 1 square foot in size.
2. Fold back the turf to expose the root zone.
3. Inspect the top 3–4 inches of soil.
4. Count the white grubs present.

How Many Grubs Are Too Many?  

If you find more than 7–8 grubs per square foot, treatment is generally recommended, or if they have attracted in a pest animal such as skunks, crows or turkeys.

Pro Tip: Check 3–4 sunny locations throughout the lawn. Beetles tend to prefer these areas for egg-laying.

Organic Grub Control Options  

Cultural Practices That Reduce Grub Pressure  

Healthy turf is the often one of the best defenses against extensive grub damage. Dense turf typically has a much larger root mass. So while grubs may feed on some roots, enough may remain to supply water and nutrients. Healthy neighboring plants can also help hold the turf canopy together, even if a few are weakened. Turf stores carbohydrates in crowns and roots, these reserves from a healthy stand of turf will also fuel new root growth after grub feeding slows or stops.

Remove Beetle Attractor Plants  

Adult beetles are commonly attracted to:

• Roses
• Japanese maples
• Grapes
• Zinnias
• Mountain ash

Reducing these attractants can help limit beetle activity around managed turf.

Improve Soil Biology  

Healthy soils support a diverse food web that naturally suppress pest populations, including:

• Ants
• Springtails
• Earthworms
• Beneficial microbes

Soil rich with biological activity doesn’t become grub free. Instead these natural enemies remove a portion of the population helping keep it in check.

Mow High  

Maintaining taller turf encourages deeper rooting and improves drought tolerance, helping lawns better withstand grub feeding.

Organic Products for Grub Management  

Cedar Cure® (Cedar Oil)  

Effective as a  curative solution when applied as a soil drench or spray. Use a backpack sprayer for spot treatments or tank sprayer for larger areas.    Grubs exposure to the cedarwood oil triggers the erosion of the exoskeleton.   CedarCure is a minimum risk pesticide compliant with EPA 25b – making it exempt from registration by the US EPA.*

grubGONE!®  

A bio-insecticide whose active ingredient is Bacillus thuringiensis subspecies galleriae (Btg) that once ingested will kill the grub.  Can be applied using a standard spreader as a preventive or a curative option. If preventive control is preferred application should be done in July-Early August  to give the Btg bacteria enough time to get in the root zone before first-instar grubs begin feeding. Applications should be performed before a rain event or watered in to avoid UV degradation. While grubGONE is OMRi listed and utilizes a natural biological control, it is registered with the EPA and requires a pesticide license.

hb Beneficial Nematodes  

A curative solution, however, require moist conditions to be effective and have a limited shelf life.  Apply using a backpack sprayer in wet conditions and keep soil moist after application. Dry weather and watering restrictions have made nematodes less viable in recent years. Beneficial nematodes enter the grubs and consume them from the inside out.   Nematodes are a 25b exempt product.*

*Always check with your state pesticide regulatory agency regarding licensing requirements, as regulations vary by state.

Final Thoughts  

Peak beetle activity is happening now, making this the ideal time to prepare for grub season. Monitor beetle populations throughout July and August, scout for white grubs in late summer, and take action if populations exceed treatment thresholds.

For landscapers, municipalities, schools, and organic lawn care professionals, proactive grub management can help prevent significant turf damage later in the season.

Need help selecting the right organic grub control strategy? Contact PJC Organic for recommendations tailored to your property and growing conditions.