In the Northeast, beetles are currently flying and will be laying eggs during July. Managing grubs is an important part of ensuring a lawn or athletic field is not overtaken by them. Beetles that tend to be of concern include:

• European Chafer: a troublesome species in New Hampshire and eastern Massachusetts
• Japanese Beetle: perhaps the most widely distributed grub species in New England
• Asiatic Garden Beetle: fairly wide spread in southern New England
• Oriental Beetle: common in the coastal regions

Grub Decline

Through the years, we’ve seen fewer instances of grubs. Potential reasons for decline:

• Removal of Attractor Plants – we recommend the removal of attractor plants, including: roses, Japanese Maple, grapes zinnias, and mountain ash.
• Healthier Soil Food Web – soils with healthy biodiversity contain potential predators to feed on beetle eggs—including earthworms, ants, springtails, fungi and bacteria.
• Drought Conditions – grubs require high soil moisture for egg survival. So, grub populations do best in soil that are consistently moist from late June into September. Perhaps another reason to avoid irrigating your lawn throughout the summer and simply allow it to go dormant.
• Mowing High – contributes to a more vigorous root mass, therefore allowing it to better withstand the chance of damage from grubs feeding on the roots.

Although the number of Japanese Beetles seems to be declining in the Northeast, they are still present. Additionally, European Chafers are night fliers, so you may not know they are flying around. Unsurprisingly, while we don’t typically see them during the day, European Chafers are showing up in our pool skimmers. Lastly, as for Asiatic Garden and Oriental beetles, we just assume they are around.

Scouting for Grubs

It is best to scout for white grubs in early – mid September.

To scout for grubs:

1. Cut three sides of a square turf section, about one square foot in size.
2. Fold back the turf and examine the roots about 3 – 4” deep.
3. Count the number of white grubs you find.

*We recommend performing this in at least 3 – 4 different spots around the lawn.

If you find more than 7 – 8 grubs per area, it is best to treat.

Treating Grubs Without Harmful Chemicals

Over the last several years, we’ve treated grubs using cedar oil out of a backpack sprayer. Previously, we had a lot of success treating with hB nematodes. But nematodes are aquatic and require moist soil conditions to move around.  Consequently, with how dry it has been the past few years, in addition to water bans, we have not found conditions favorable for them be an effective treatment option. Need help managing grubs without pesticides? Contact PJC!