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Learn Your Lawn: Tropical Sod Webworms

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What Are Tropical Sod Webworms? 


The Tropical Sod Webworm is a common pest in residential lawns, especially in warm and humid regions. These small caterpillars, measuring about ¾ inch long, feed on grass blades, causing brown patches in the lawn. They are most active during the warm months of the year, and they thrive in areas with high humidity and rainfall. The damage is usually most severe in areas that are stressed by drought or heat and receive a lot of sun exposure. Tropical Sod Webworms prefer to feed on grasses like St. Augustine, Bermuda, and zoysia, which are commonly found in residential lawns. The larvae form silk-lined tunnels in the soil, where they pupate and emerge as moths.


What Is The Life Cycle Of The Tropical Sod Webworm?


The entire life cycle takes about 6 to 8 weeks, depending on the temperature and other environmental conditions. The pest can have several generations per year, with the peak season for damage occurring during the warmer months.

  • Egg Stage: The female moth lays her eggs on the blades of grass, usually in the evening. The eggs are white or pale green and oval-shaped. They are typically laid in groups of 5 to 20.

  • Larva Stage: The larvae emerge from the eggs after a few days and begin to feed on the grass blades. They are light green or brown and have dark spots on their bodies. As they grow, they molt several times, shedding their old skins.

  • Pupa Stage: After about 2 to 4 weeks of feeding, the larvae spin cocoons in the soil and pupate inside them. The pupae are brown and about ½ inch long.

  • Adult Stage: After 1 to 2 weeks, the adult moths emerge from the pupae. They are small, brownish-gray moths with wingspans of about ¾ inch. The adult moths mate and lay eggs, starting the cycle all over again.


How Can I Control Tropical Sod Webworms In My Lawn?


Tropical Sod Webworms are ideally controlled early in their life cycle, before severe damage occurs. A change in cultural practices can help deter infestations of this pest. However, if damage becomes severe, other forms of control may be necessary.


A thick, healthy, well-maintained lawn is always the best line of defense. This can be achieved through beneficial cultural practices, which include:

  • Core Aeration: Aerating your lawn can improve soil drainage and help reduce the likelihood of lawn diseases. This will also alleviate soil compaction and allow water and nutrients to penetrate deeper into the soil.

  • Fertilize Regularly: Regular applications of Weed Man’s specially formulated, slow-release granular fertilizer will help provide your lawn with adequate nutrients. These applications are timed specifically to avoid over fertilizing the lawn.

  • Watering: Under normal circumstances, you should be watering your lawn a few times per week for 30-45 minutes in each area. During hot and dry periods, most lawns should be watered as much as required to maintain its desired green color. Always water in the early morning so the turf has time to dry by nightfall.

  • Mowing: Maintain a regular mowing schedule with a razor sharp blade. Never remove more than a ⅓ of the grass blade at each mowing.


Recommended Mowing Height

Common Bermudagrass - ¾ to 1¼ inches

Hybrid Bermudagrass - ½ to 1½  inches

Centipedegrass - 1 to 2 inches

Zoysiagrass - 1 to 2½ inches

St. Augustine - 3 to 4 inches

Fescue - 3 to 4 inches


Your local Weed Man professional may be able to offer other solutions and recommend the best form of treatment that is available to improve the conditions of your lawn.