Tropical Sod Webworms

Tropical Sod Webworms in Texas Lawns

It’s finally fall in South Texas.  The temperatures are a little cooler, there’s more rain in the forecast, and you may be thinking “Finally, my lawn will get a break from a summer of unbearable heat.”  We hope that’s the case, but with warm-weather turfgrass, especially St. Augustine, be on the lookout for tropical sod webworms.  These caterpillars, like their relative the fall armyworm and cutworms, are destructive pests to newly laid sod and established lawns.

After their eggs hatch, tropical sod webworm larvae begin to feed on turfgrass leaves at night or during overcast parts of the day.  It is at this phase in the lifecycle when they are most destructive to lawns and can cause a tremendous amount of damage in just a few days.  In addition, with a 28-day lifecycle, several generations of these webworms can be produced in a single season.

Look for these signs to identify tropical sod webworm activity in your lawn.

• Affected areas in the lawn will have shorter turf than unaffected areas
• Leaf blades may have a notched appearance due to webworm damage
• Areas next to shrubs or flower beds may show the first signs of damage since the webworms rest and lay eggs in these areas
• Use a soapy water mixture of one tablespoon of lemon-scented dish washing liquid in one gallon of water to flush caterpillars out to the soil surface for identification

Treatment for tropical sod webworms is most effective during the larval stage.  For a complete list of products visit https://agrilifeextension.tamu.edu/wp-content/uploads/2017/06/2016-guide-weed-insect-pest-control-in-turfgrass.pdf.  When considering treatment options avoid broad spectrum insecticides as these may negatively impact beneficial insects and other wildlife.

For more information on this pest visit https://aggieturf.tamu.edu/wp-content/uploads/ESC-047.pdf or http://entnemdept.ufl.edu/CREATURES/ORN/TURF/Tropical_sod_webworm.htm.

Source and photo credit: https://aggieturf.tamu.edu/wp-content/uploads/ESC-047.pdf

For research-based answers to questions or problems in your home landscape visit https://fbmg.org/ask-a-master-gardener/, email FortBendmg@ag.tamu.edu, or call the Master Gardener Hotline at 281-341-7068 to submit your questions and photos. Our trained Master Gardener volunteers are available to answer your questions.

Boone Holladay
Texas A&M AgriLife Extension Service
Fort Bend County Extension Agent – Horticulture
JB.Holladay@ag.tamu.edu
(281) 342-3034, ext. 7034
https://fortbend.agrilife.org