Gardening Tips: November/December

Stages of Webworm Larvae

Meadows Place has been invaded by a small but very destructive little critter called the sod webworm. The moth or adult form of these webworms can be seen in the early evening fluttering over the grass. Damage is done primarily in the hot months of July and August by the slender caterpillars which reach about 1 inch in length. They feed on your grass primarily at night. If you have damage to your lawn and have determined it is not chinch bugs it is probably sod webworms.

They live in the thatch just above the soil, where they spin a light webbing and feed on the undersides of grass leaves. The damage will first appear as small irregular brown spots in the grass. The damage can spread rapidly and will quickly destroy large portions of your lawn. It is most prevalent in areas that receive plenty of direct sunlight. Heavily shaded areas are seldom affected. Damage will show up in September and October after the hot and dry months of July and August.
 
How can you determine if your yard is infested? You may notice the adult moth zig zagging over the turf at dusk. You can examine the thatch layer and the top one inch of soil for larvae, silken tubes and webbing.

To confirm mix ¼ cup of household detergent with two gallons of water. Mark off two separate areas, one square yard each. Apply one gallon to each of the areas. The solution will irritate the caterpillars, causing them to move to the surface within 5-10 minutes. Fifteen or more larvae per square yard in a healthy turf would justify treatment.

There are several organic methods to treat these pests.
1. For light or moderate infestations, combine 2 tablespoons liquid soap into1 gallon tap water. Mark one square yard and sprinkle the mixture to draw the caterpillars to the surface. Then rake and destroy.
2. For a more extensive infestation, Spinosad, a biological agent derived from fermentation, is effective. Mix 2 oz. to 1 gallon. Three gallons will treat 1,000 sq. ft.  Refrain from heavy watering and mowing for 12 to 24 hours.


​If insecticides are used, please take every precaution and follow the label directions explicitly. Insecticides can be applied in either spray or granular form.  The turf should be mowed and clippings removed to enhance insecticide effectiveness. Thoroughly water lawn ½ - ¾ inch prior to application. This will move the webworms closer to the surface. Apply in the late afternoon.

If the damage is from the tropical webworms, a liquid spray applied to the leaves is suggested. Spray solutions can be applied with a garden hose sprayer. Apply at least 15 to 25 gallons of insecticide-water solution to 1,000 square feet of grass.  Use insecticides containing acephaqte (Orthene), bendiocarb (Dycarb or Turcam), carbaryl (Sevin), or the microbial insecticides Bacillus thuringiensis ssp.  Kurstake (B.t.k.) and ssp. Aizawai (B.t.a.) * The microbial insecticides are specific for caterpillars thus do not harm non-target anthropods or animals Consult the directions given on the container label to determine the approved rate of insecticide application.*

*The insecticide application recommendations are taken from Texas Cooperative Extension which is part of the Texas A & M University System.

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