Sod Webworms May Soon Be in a Yard Near You!

Sod Webworms May Soon Be in a Yard Near You!

Tropical sod webworms (Herpetogramma phaeopteralis) have recently been encountered in a number of yards in the Panhandle. The worms usually feed in large groups and unfortunately, the first, and basically the only, sign of damage is often a large area of shorter grass due to their feeding. The arrival time of sod webworms is also unfortunate because they are part of a group of caterpillars that successively attack turf including fall armyworm (Spodoptera frugiperda), striped grass loopers (Mocisspp.), and the fiery skipper (Hylephila phyleus).

Sod webworm feeding damage in the turf thatch layer. Photo Credit: University of Florida/IFAS Extension.

Sod webworm feeding damage in the turf thatch layer. Photo Credit: University of Florida/IFAS Extension.

Description
Larvae

Caterpillars are light yellow to orange with brown spots on each body segment and they have a dark, orange-brown head. They will grow to a full length of slight less than 1/2 inch.

Pupae

The reddish brown pupae are about about 1/4 inch long. The pupae are typically found in the upper thatch layer.

Pupa found in cocoon in St. Augustinegrass thatch. Photo Credit: Steven Arthurs, University of Florida/IFAS

Pupa found in cocoon in St. Augustinegrass thatch. Photo Credit: Steven Arthurs, University of Florida/IFAS

Adults

The moths brown with splotchy wings and are about 3/4 inch wide.

Control

Sod webworms are difficult to control because of their spontaneity.  However, in the lawn they hide in the thatch during the heat of the day.  Over watering and fertilization can increase the amount of thatch.  It is important to follow UF/IFAS guidelines for home lawn management.

The first line of defence is healthy turf. Proper fertilization, irrigation, and mowing height can decrease susceptibility of turfgrass against sod webworm. Over-fertilization is a common cause of caterpillar outbreaks in lawns. Cultural practices such as thatch removal by vertical mowing can help eliminate populations. Eggs are laid on grass blades and removal of grass clippings might also reduce populations.

Numerous chemical control options are available, but softer chemicals such as insecticides containing the bacteria Bacillus thuringiensis are recommended as a first line of defense. Insecticides should be applied in the morning or evening during feeding time. For additional control strategies and basic information please visit the UF/IFAS Sod Webworm Publication.

 

Tropical Sod Webworms Active in Local Lawns

Tropical Sod Webworms Active in Local Lawns

Tropical sod webworms have been active in local lawns during the past few weeks here in North Florida. All of our warm season turf grasses are susceptible to these pests.

Sod webworms are not consistently a problem every year. Some years their numbers are low enough that they are not a problem. Some years we do not see them at all. Those years when they are a problem, it’s usually not until late summer and early fall that they become active and they may continue to feed on lawns until frost occurs.

Fall armyworm. Photo credit: Frank Peairs Colorado State University, bugwood.org.

Fall armyworm. Photo credit: Frank Peairs Colorado State University, bugwood.org.

Fall armyworms and sod webworms can attack at the same time. Sod webworms are the smaller of the two species, reaching a length of about ¾ inch. Armyworms grow to ½ inch in length. Both of these caterpillars are greenish when young, turning brown at maturity. Armyworms generally have a light mid-stripe along their back with darker bands on either side of the mid-stripe. Their feeding is similar, resulting in notched or ragged leaf edges.

Sod webworms tend to feed in patches while armyworms cause more scattered damage. Sod webworms feed at night while armyworms will be seen feeding during the day. Sod webworm caterpillars rest, curled up near the soil surface during the day. Adults of both species are fairly small grayish to brown moths.

If your lawn has damaged spots, look closely for notched leaf blades from their chewing. You may first notice a patch in your lawn that looks like it has been mowed extra low. Closer inspection reveals grass blades that are chewed away. Caterpillar feeding on zoysiagrass shows up more as translucent whitish tan areas on the surface of individual blades more so than as notched blades.

Fall armyworms and sod webworms can be controlled with the same insecticides as the other lawn insects. But you also may use insecticides that contain Bacillus thuringiensis; a bacterium that only kills caterpillars. Control should only be directed against the caterpillars, not the non-feeding, flying adult moths. Always follow the label directions and precautions for any pesticide you use.

For more information on lawn caterpillars contact the UF/IFAS Extension Office in your County or visit http://edis.ifas.ufl.edu/topic_tropical_sod_webworm.