How To Get Rid Of Sod Webworms

If you invest time and effort into making your lawn look amazing, it can be discouraging when you notice one day that your grass is dying and looking unsightly. One of the most prevalent culprits of this problem is a tiny nuisance known as the sod webworm.

Sod webworms can cause tremendous destruction, but they’re relatively easy to control, primarily if you start your sod webworm control mission immediately after the sod webworms have hatched. Like all other pests, you might need to learn how to get rid of sod webworms.

What is a sod webworm?

Tropical sod webworms are turf caterpillars – the larval or caterpillar stage of a small white-brown moth. They grow up to 1-inch long and vary in colour, from green to brown or gray. They have dark heads and tiny dark spots across their bodies.

They are a typical pest in residential lawns and are rowdy during warm, humid weather, chewing grass and eventually creating brown, patchy dead spots.

These caterpillars hide beneath the surface of the lawn in silk-lined tunnels, appearing just long enough to skeletonize or feed on grass blades. The webworm likes to graze warm-season grasses, specifically on recently installed sod, lawns, sports fields, golf course greens, and cemeteries. They are significantly dominant in sunny locations or south-facing slopes.

Sod Webworm Lifecycle

Nearly mature larvae continue to live in the soil through the winter. They resume feeding as temperatures rise in April or early May until their growth is complete.

Sod webworm moths lay eggs in spring. Eggs hatch in just a week, and the adult sod webworms begin to feed after about ten days. First-generation larvae feed until mid-summer, which causes the majority of issues in turfgrass as they are just the first batch of cropping worms.

Pupation occurs from late June to early July. Adult moths rest during the day in deep grass and fly in a zigzag manner across lawns at sunset or just after dark. Females may drop up to 200 eggs in the grass as they pass.

The second generation emerges before winter. The grass is already withered, and continuous feedings cause more evident damage to your yard.

Lawn moths may produce several generations per season, with many opportunities for lawn damage.

Sod webworm control should center on the larvae, not the adult moths.

Signs of Sod Webworm or Lawn Moths Manifestation

A mowed patch of grass vulnerable to sod webworms.
  • The first signs of sod webworm feeding are detected in spring. After they overwinter, they appear in the spring with a huge appetite.
  • You’ll notice small brown patches on your lawn. Larvae feast at night on grass leaves and stems near the soil surface. The patches start as irregular spots marked by very short grass and grow to the size of a baseball. With heavy infestations, you’ll soon have large areas of dead grass.
  • You’ll see sod webworm moths flying around in the late afternoon or early evening over the sod. Likewise, you might see tiny holes in those patches because birds hunt for sod webworm larvae.
  • The lawn damage may develop any time from May through to September, or even later in the season because different generations of these worms are born every summer.

Inspecting your Sod for these Lawn Pests

Due to the timing of the damage, some people assume their lawn issues are caused by drought stress.

To find out if sod webworms are the reason, inspect the area for the existence of silk webs and tiny green pellets (worm feces).

Sod webworms can hole up in dens when they are dormant. To expedite your hunt, lure them out:

You can use a liquid soap solution (3.78 L of water and two tablespoons of dish soap) and pour it over about a square foot of your turf at the edge of the damaged area. If sod webworms are present, they’ll pop up to the surface a couple of minutes later.

Controlling Sod Webworms

If you believe sod webworms have started a colony in your yard, it’s paramount to get rid of them right away. Here are some practices you can consider.

Dethatching your lawn

A pile of mulch next to a pair of boots and a rake, with possible infestation by sod webworms.
Dethatch your lawn with a garden rake if the thatch layer is more than 1/2 inch deep. Push the rake deeply down through the sod to reach the thatch layer that lies beneath. Scrape until little to no thatch emerges from the grass. Dethatch your lawn annually to prevent a thick layer of thatch, which is appealing to sod webworms, from building up.

Water regularly

Sod webworms grow in dry thatch so do your best to water your lawn regularly to prevent it from drying out. If the weather is hot, you might want to water your garden every hour of the day.

Most light to moderate infestations of sod webworms can be addressed by turf irrigation.

Apply endophytes

Endophytes are a particular type of fungi living in grass. They are often not harmful, but they can fend off pests, including sod webworms. Spread the seeds in your existing sod and water the area until the grass is rooting.

You can purchase this useful grass seed at most garden supply stores. Observe all guidelines on the label, specifically if you have pets that may sometimes eat grass. Too much endophyte consumption can be toxic to some animal species.

Introduce natural predators

For those uncertain about applying pesticides or insecticides, choose the biological pest control option to impede the damage caused by sod webworms. These biological options take time to work but perform well for controlling sod webworms. Most importantly, they’re safe for people and animals, and are environmentally friendly.


Use nematodes at the first sign of lawn damage. These tiny worms can kill sod webworms, though they won’t harm beneficial insects. These small organisms use the caterpillars as hosts, inducing their death.

They’re most potent against recently developed caterpillars, so use them as early as you’ve verified your grass has sod webworms.

They’re temperature-sensitive and must be used at night when it’s cooler. Water the lawn a day or two before applying the nematodes and lightly water right after application.

With the proper application, the nematodes can create a healthy colony that will protect your lawn for ages.

Bacillus thuringiensis

You may also spray the lawn with Bacillus thuringiensis during the early larvae appearance. It is a soil-dwelling bacterium, producing a natural toxin which paralyzes the caterpillars. That being said, it appears to have little to no effect on older larvae, so learning the sod webworm lifecycle is the answer to gaining control.

Shoot Bacillus Thuringienssis at sunset or early evening so that sod webworms can receive direct sprinkling from their burrows when they appear. Apply the recommended dose on your lawn. Even if you implement the bacteria at the ideal time, you might have to repeat the procedure at 5-7 day intervals until all the webworms are gone.

Apply an insecticide

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If you notice vast grass damage, you may have to apply an insecticide. Pesticides are the last option when biological controls don’t work.

Not all pesticides are created equal. Avoid broad-spectrum pesticides, which eradicate beneficial insects that could help repel the sod webworm infestation. Use a pesticide specifically designed for effectiveness against the pests, like those containing acephate, bendiocarb, or carbaryl. It’ll assure you’re not unintentionally causing more damage to your yard than good.

Watering the sod before applying an insecticide will help the chemicals creep into the grass smoothly. It will also push the caterpillars to the surface.

You can use either a spray or a granular insecticide.

  • If you apply a spray solution, use at least 57–95 L(15–25 gallons) of insecticide per 1,000 sq. ft. (93 m2) of grass.
  • If you choose a granular insecticide, use a push broadcast spreader to spread the granules, like applying fertilizer. For smaller patches of lawn, you can have a hand spreader. Often granular insecticides are followed by approximately an hour of light watering to wash the active ingredient and reach the pests.
The larvae feed primarily at night. Thus, effectively treating a severe infestation with chemicals means using insecticides during dusk or night to ensure poison intake.

Before applying chemicals, we recommend wearing protective equipment to protect yourself during application. And keep leftover insecticides in the original container and out of the reach of children and pets.

Preventing These Sod Webworms From Occurring

There are approaches to maintaining your lawn’s quality after detecting sod webworms. The healthier your lawn is, the better it can endure sod webworms and other nuisances without prolonged damage. Hence, ensure regular lawn maintenance.

  • You have to begin with these preventive techniques when spring commences, otherwise they’ll be worthless, and you will have to adopt other ways to eradicate these worms.
  • Habitually water your plants, though never overwater them because overwatered lawns are inviting to adult moths ready to lay eggs.
  • Mow your grass at the height of 3 to 4 inches. Trimming your lawn too short can result in thin turf and scalping. This makes your grass wither faster, making it more vulnerable to pests.
  • Implement the correct type of fertilizer for your lawn’s maturity and the degree of cold or heat stress it’s going through.
  • Dethatch the lawn once a year and aerate during spring, fall, or both.
  • If you reside where these pests are frequent, you may need to plant a turfgrass immune to the worms. Use endophyte-enhanced grass for your lawn. Not all grass species possess endophytes. Kentucky bluegrass doesn’t; however, tall fescue, fine fescue, hard fescue, and perennial ryegrass varieties do.

Wrap Up

It’s vital to observe and care for your lawn to keep pests from appearing. Sod webworms are something that most homeowners have to ward off at some point, specifically in their lawns. This article sheds light on how to get rid of sod webworms successfully.


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