How to Control Insects Above the Grass and Grubs Below the Roots

A healthy lawn can look great one week and suddenly show signs of stress the next: thinning turf, brown patches, spongy areas, or increased insect activity. While drought, disease, and mowing habits can all play a role, insects and grubs are often the hidden cause. Some pests live and feed above the lawn’s surface, while others, like grubs, cause damage below the surface by attacking the root system. That’s why effective insect control starts with understanding where the problem is happening: above the grass or below the thatch.

Not all lawn insects damage turf in the same way. Surface pests live and move above the thatch layer and may include insects such as ants, spiders, ticks, billbugs, chinch bugs, beetles, and similar pests. These insects are typically treated when pest activity or visible turf damage first appears.

Subsurface pests live below the thatch layer, often in the soil where they can feed on grass roots. White grubs, mole crickets, June beetles, armyworms, and similar pests can cause serious lawn damage because their activity may go unnoticed until the turf begins to brown, thin, or pull away from the soil.

Grubs are the larvae of beetles, commonly including Japanese beetles, June bugs, or European chafers. These white, C-shaped larvae feed on grass roots, which can weaken the lawn from below before damage becomes obvious above ground.

Common signs of grub damage include brown or patchy turf, a spongy feel underfoot, grass that peels back like carpet because roots have been eaten, and increased digging from animals such as raccoons, skunks, or birds searching for grubs.

Late summer through early fall is an important window for treating active grub problems because grubs are often smaller and closer to the surface, making curative treatment more effective.

Many lawn insect control products are designed to target either surface insects or below-surface pests, which can make treatment confusing if you are not sure exactly what is causing the damage. DuoCide® is a solution for both types of pests because it combines bifenthrin and carbaryl in a multi-mode formula designed to control insects above and below the lawn’s surface at the same time. With a single application, DuoCide controls more than 50 common lawn pests, including grubs, ticks, fire ants, mole crickets, fleas, European crane flies, and more.

DuoCide uses DG 'Dispersing Granule' Technology. When watered in, each granule breaks apart into thousands of microparticles that move through the turf canopy and into the soil profile, helping deliver the active ingredients where pests are active. This smaller particle movement helps improve coverage and supports more effective contact with pests both at the surface and below the thatch layer.

Application timing depends on the pest you are targeting. For surface pests, apply when insects or damage first appear. For subsurface pests such as grubs, application is recommended when damage is first noticed or roughly 10–14 days after egg-laying, depending on the pest.

DuoCide is especially useful for late-summer and early-fall applications because it can serve as a rescue treatment for homeowners who may have missed an earlier preventive application window.

A strong lawn is more resilient against insect pressure. Mowing high, watering deeply, avoiding over-fertilization, dethatching when needed, and using preventive grub control in late spring or early summer can help reduce future outbreaks.

Lawn insects can attack from multiple levels. Surface pests may be visible above the grass, while grubs and other subsurface insects can quietly damage roots below ground. DuoCide offers a practical approach because it is designed to control pests both above and below the lawn’s surface with one application.

By identifying the signs early, applying at the right time, watering in properly, and repairing damaged areas after treatment, homeowners can stop insect damage in its tracks and help their lawn recover stronger for the season ahead.