The Tropical Sod Webworm, Herpetogramma phaeopterali, is the most common
caterpillar attacking turfgrass in the Central Florida area. They attack all grasses,
but seem to prefer Crabgrass and St. Augustinegrass. Armyworms cause similar
damage, but are more aggressive than the Sod Webworm, moving more quickly
and thoroughly through the grass with their feeding.
Sod webworms and Armyworms are usually not a problem in the Orlando area
of Central Florida until late May or June, and have peak feeding periods in July or
August. Their damage decreases in the fall, and ends once cooler weather arrives.
Injured grass has notches chewed along the sides of the blades, or is eaten back unevenly.
They feed only at night, and rest in a curled position near green fecal matter on the
soil surface during the day. The life cycle requires five to six weeks, and there are several
generations per year.
Probably the first thing you will notice when Sod Webworms have arrived is that it
seems someone has entered your lawn while you were sleeping, and scalped it in
areas with a weed eater (string cutter). It is not uncommon to go to bed at night with
the lawn in good condition only to wake up to patches of the lawn missing grass blades
in the morning. You may also have noticed several weeks earlier that there were some
small brown moths flying through the shady areas of your grass, or emerging from
The larvae and the adult moths are the most noticeable stages of this pest. The
larvae are the only stage that causes damage. They are 3/4" long when mature and
have translucent bodies that appear greenish from a diet of green grass blades. The
moths have brown colored wings and measure about 3/4" long.
Sod Webworm Control
First, don't panic if you suspect you have Sod Webworm or Armyworm damage.
Sod Webworms and Army worms usually cause only temporary cosmetic damage
to our turfgrasses, and do not by themselves cause any permanent damage.
Turfgrass can receive permanent drought damage in the hot, summer months if the grass
does not receive adequate moisture during the time of Sod Webworm feeding. New sod
may also receive permanent damage if Sod Webworms or Armyworms feed before the
grass can become established. This is another reason that sodding during the hot,
summer months is a risky proposition.
Sod webworm damage cannot currently be prevented. Once Sod Webworms or
Armyworms begin feeding, they are easy to control with the proper application of
many available insecticides. The damage usually is not noticeable following a couple of
weeks of growth after treatment. Also, most lawns will fully recover from worm damage,
even if an insecticide is not applied. It is important to keep a lawn well-irrigated during
worm damage to prevent subsequent drought damage that can occur.
The presence of moths doesn’t necessarily indicate that there is worm damage,
or that control is needed. The larval stage of the insect is the only stage that can be
controlled, and there must be larvae feeding before an insecticide can be applied.
Many times the moths in someone’s lawn will lay eggs in a neighbor’s lawn, or the eggs
won’t develop into worms.
One of the benefits of being a Dr. Jack’s customer is that if you receive Sod Webworm
damage between one of our regularly scheduled services, we will return and treat at no
extra charge. Simply give us a call! 407-422-3641.
At Dr. Jack's, "We have Service Down to a Science".