caterpillar | Gardening in the Panhandle

What’s Eating My Lawn?

by Taylor Vandiver | Sep 9, 2014

What’s eating my lawn? Does your grass look ragged in areas, as if someone randomly used a weed-eater here and there? Are you noticing brown patches that have a closely clipped appearance compared to other areas of your lawn? Your turf may be playing host to Tropical Sod Webworm.

Sod webworm damage in a home lawn. Photo courtesy UF/IFAS.

Sod webworm damage is subtle at first. You have to look closely to notice larval feeding damage. However, an easy indication of their presence is the light tan/brown colored moths, which are the adult stage of the pest. You may see them fly up as you walk through your lawn or if you disturb a nearby bush. The moths do not cause any damage to the turf, but they are depositing eggs, which will result in their offspring, the caterpillars, who do all the chewing damage.

The larvae are gray-green and have spots on each segment. The mature larvae can be up to 1 inch in length. Larvae will curl up in the soil during the day and feed at night. So if you happen to notice caterpillars feeding during the day, it’s probably not sod webworm. You will notice chewed notches along the leaf blade, holes in the leaf and even leaf blade skeletonizing. The older the larvae are, the more they will eat. Damage may start out as a ragged appearance in your turf, which can be hard to diagnose. However, if left unchecked, sod webworm can cause considerable injury to your lawn.

Sod webworm larvae. Photo courtesy UF/IFAS.

If you are uncertain of their presence you can always use a soap drench to flush out larvae. Mix 2 tablespoons of dish soap with 2 gallons of water and pour it over a damaged area (about 3 square ft.). The soap mixture will irritate the pest and bring them to the surface so you can easily identify them. If nothing appears in the area tested move to another damaged site and try again. Here is a link to a video that will give more information on identifying Tropical Sod Webworm.

Tropical Sod Webworm is considered a pest of all warm-season turfgrasses. However, St. Augustinegrass is most commonly affected. The best way to prevent a pest infestation is to use proper cultural maintenance practices for your lawn type. However, if the pest does appear, chemical control should be targeting the larvae stage of the pest. There are multiple products marketed to control lawn caterpillars. However, you may want to consider using B.t. (Bacillus thurengiensis), which is a bacterium that will only harm caterpillars and not bother beneficial insects that may be in your lawn. For more information you can contact your local extension office.

Pecan Tree Visitors

by Julie McConnell | Jul 1, 2014

Panhandle residents have seen caterpillars in abundance this June. One common visitor to pecan trees is the Walnut Caterpillar Datana integerrima. The walnut caterpillar has a very narrow host range and feeds only on trees in the Juglandaceae family which includes walnut, pecan, and hickory trees. They are sometimes seen on other plant material, but feeding on non-host plants is unlikely.

Walnut caterpillar feed on the leaves of host trees through several growth stages and molts until they have reached the final larval instar and are ready to pupate into an adult moth. Their color changes from light green when newly hatched to reddish-brown to almost black with long white hairs as they mature. The caterpillars group together in large masses and may hang from each other and dangle from the tree branches when molting. Instead of creating a cocoon in the tree, the walnut caterpillar moves to the ground beneath the tree and burrows into the soil or leaf litter to pupate and emerges later as a moth.

What can you do if your pecan tree is hosting walnut caterpillars?

Although the numbers seen on trees may be alarming, a healthy tree can tolerate some feeding damage. Stripped branches may increases the chance of a lower yield of fruit because the removal of leaves does reduce the amount of energy the tree can produce, but overall health of the tree should not be significantly affected. However, many homeowners find falling caterpillars and their excrement unappealing and may decide to take steps to manage the population.

There are several natural enemies that feed on caterpillars, so avoid using a broad spectrum insecticide that might harm predatory insects and other animals. Consider using a biological control product such as Bt (Bacillus thuringiensis) that is only lethal to caterpillars. Other methods are “pick and squish” or drowning in a bucket of soapy water. Next year, in the spring, watch for masses of tiny green eggs on the underside of leaves and remove and destroy them before hatching.

For more information visit USDA Forest Service Forest Insect & Disease Leaflet 41 “Walnut Caterpillar”