Sod Webworm Biology
The sod webworm is the larva of those little tan moths that flit about the lawn when disturbed as you walk in the lawn. The moths are a nuisance but harmless and there is no effective control for the moth. The adult moths lay eggs in the lawn with the best chance of survival of eggs and larvae - concentrating eggs in prime lawn areas.
Most Active May - October
In Pinellas County, lawn moths are most active laying eggs from May through October. During these times, the egg-laying and hatching are constant and the population can expand logarithmically in prime areas of the lawn. A few sod webworms here and there are not a problem. However, when the sod webworm population explodes, they can mow your lawn for you.
The Damage
Sod webworm damage is circular in appearance, can be any size from a few inches to an entire lawn, and often a distinct grey or tannish color. The most distinctive symptom is the lawn is shorter in the damaged areas – this is because the sod webworms are cutting down the St Augustine grass.
Sod webworms feed on St Augustine grass leaves. However, instead of eating the entire leaf, they chew across it near the stem and move on to the next leaf. This gives the area a “mowed” appearance. Then the leaf that has been cut turns grey to tannish brown giving the damaged area a distinct color.
If you look closely at the damaged area you will see the cut marks on leaves and stems where the sod webworm is feeding. Looking further into the canopy you’ll find the little green caterpillars curled up at the soil surface.
No Need to Panic over Lawn Moths or Sod Webworms
No need to panic over the moths or sod webworms – a few sod webworms will not harm. In areas where the population is high, they can damage the lawn, however, St Augustine will fully recover from sod webworm damage if treated. Left untreated, the sod webworms will feed on stems and roots and destroy the lawn.
For the DIY
The best treatment is to spray the damaged area with an insecticide – just about any will do – and let the sod webworms feed on the treated grass overnight. Within a week the grass will return to a normal appearance. Treat as often as you see damage.
Professional Help
If you have a professional - like our sponsor Barefoot Grass - they will be active at keeping sod webworms and other insects like chinch bugs, grubs, and mole crickets under control all season long.
