How do I know if grubs are gone after treatment?
Written by
Nguyen Minh
Reviewed by
Prof. Martin Thorne, Ph.D.Verification of grub control requires systematic inspections to be conducted after treatment. I teach clients to allow 10-14 days after treatment to get the full effectiveness of the treatments. Look for indicators of success, such as regrowth of roots, reduced animal activity, and the absence of C-shaped larvae. Proper verification prevents an unnecessary celebration and wasted effort.
Timed Inspections
- Examine treated areas 10-14 days post-application
- Recheck borderline zones after 21 days
- Conduct dawn/dusk inspections when grubs surface
- Focus on previously damaged sections first
Visual Confirmation
- Look for absence of white C-shaped larvae
- Check for new white root growth
- Observe reduced bird/raccoon activity
- Confirm turf regains firm texture
Testing Methods
- Perform soapy water test in suspicious areas
- Use tug test to check root reattachment
- Apply heat lamp test for dormant grubs
- Compare before/after soil samples
Perform the soapy water test in questionable areas. Mix 2 tablespoons of dish soap per gallon of water. Pour the solution over 1 sq. ft. areas. Wait for 10 minutes. If the grubs do not surface, the treatment is considered successful. I mark the test areas with flags for consistent monitoring.
Interpret animal behavior changes accurately. A reduction in digging means a decrease in the grub population. An increase in bird activity might mean that maggots are dying out on the surface of the soil. Be sure to note patterns on my chart of daily observations, including the time, species, and location of animal visits.
Ensure that you promptly manage treatment failures. If the grubs remain after 21 days, apply fewer treatments using a different chemistry. I alternate between carbaryl for quick knockdown and imidacloprid for residual control. Always water the retreatment immediately and restrict access to the area to pet traffic.
Utilize preventative monitoring following confirmation. I schedule monthly inspections during heavy seasons. Maintain a mowing height of 4 inches and proper irrigation. A healthy turf will naturally resist future infestations more effectively than a stressed lawn. Your efforts will ultimately pay off.
Read the full article: Effective Lawn Grub Treatment Guide
