Sod webworms love to feast on your lawn
BY THERESA FRIDAY Santa Rosa County Extension Agent

It's not just people that like a nice green lawn. Several pest insects are attracted to our lawns and feed on the grass. One insect that has been active in the last few weeks is the sod webworm.

The sod webworm has an interesting life cycle. The adult is a dingy tan to gray colored moth. The moths do not cause damage to the lawn. However, the female moth flies over lawns dropping her eggs. The eggs hatch into very hungry caterpillars that feed on the grass blades.

The first noticeable injury is usually chewed notches along the edge of the leaves. This creates a ragged appearance that may be hard to notice at first.

As the population increases, sod webworms quickly strip the foliage, leaving only bare stems. The damage is never uniform throughout the entire lawn, so look for a close-clipped appearance in some areas while others grow at a normal height.

Flocks of birds that frequently return to a turf area may also indicate that sod webworms or other caterpillars are present.

This is a crafty pest. First, they feed only at night. During the day they can be found hidden on the soil surface. If leaf feeding caterpillars are seen on the lawn during the day, you can be assured that they are not sod webworms, but some other species such as armyworm or grass loopers.

Also, sod webworms are usually present for several weeks before they are noticed, feeding most heavily during the last week of their caterpillar stage.

If left unchecked, a heavy infestation of sod webworms can severely damage a lawn. The blades can be eaten down to the runners and the grass must use extra energy in an attempt to recover. It is sometimes hard for the grass to recover so late in the growing season.

Control of sod webworms is not especially difficult. A combination of proper cultural practices that discourages them, weekly inspections and the careful use of the right insecticide, when necessary, can reduce or eliminate any threat from this lawn pest.

The best way to deal with sod webworms or any pest is to practice proper cultural techniques. Follow fertilization and irrigation practices that produce moderate, but not extremely lush growth.

Monitor the lawn by inspecting for sod webworms once each week during late summer and early fall. Look for off-color areas and determine if these patches have a ragged or chewed appearance.

Part the grass in several of the suspect areas and closely examine the soil surface. The larvae are small greenish caterpillars with many black spots. They may be very smallwhen young, with a full sized caterpillar being less than one inch in length.

Sometimes the caterpillars are difficult to find, even when present in damaging numbers. This is because they curl up in a 'C' shape and hide in the thatch, as well as on the soil surface. Small green pellets of their excrement are also present near the soil surface and this material is often easier to find than the caterpillar.

If all else fails and you still suspect sod webworms, use a soap flush in order to more thoroughly check these areas. Mix 2 tablespoons of liquid dishwashing soap in 2-gallons of water and drench four square feet of area with this solution. If any caterpillars are present, they will emerge to the grass surface and can be easily detected.

Start treatment as soon as these pests are noted. Some control products include B.t. (Dipel or Thuricide), carbaryl (Sevin), bifenthrin (Talstar) or lambda-cyhalothrin (Spectracide Triazicide). Always follow label directions exactly.