Test Your Knowledge - August

Oleander caterpillar
Oleander caterpillar
Anne W. Gideon, Bugwood.org

Yes, this is an oleander caterpillar!

The oleander caterpillar (Syntomeida epilais) is a major pest of oleanders in the coastal region of the southeast. Oleanders are the preferred host, but Syntomeida epilais have also been reported on bougainvillea and mandevilla. In South Carolina most damage occurs during the summer months.

The adult moth is purplish with white dots on greenish black wings and a 1¾- to 2-inch wing span.

Adult moth of oleander caterpillar
Adult stage of the oleander caterpillar
Sally Tucker, Bugwood.org

Female moths lay 25 to 75 eggs on the lower surface of leaves. When the caterpillars first emerge, they feed in groups on the underside of the leaves turning them brown and skeletonizing the foliage. If the caterpillars are allowed to grow, they can quickly defoliate the plant. Defoliation will not kill an established plant, but it will weaken it, making it more susceptible to other pests. Oleander caterpillars reach up to 2 inches long and are orange-red with tufts of black hairs which arise from black bumps on the body. The feeding period for each generation averages about 19 days. Multiple generations overlap throughout the year, which means that adult moths and caterpillars may be seen at the same time. This pest is usually killed back by cold winter temperatures in South Carolina.

Oleander caterpillar
Oleander caterpillar
Anne W. Gideon, Bugwood.org

Even though the caterpillars are hairy, they are harmless to humans and can be picked off by hand. It is best to remove the caterpillars as soon as an infestation is detected. Bacillus thuringiensis (B.t.) is a low toxicity biological control that is very effective if the caterpillars are found when young. Brands of B.t. concentrates that are available for homeowners to purchase include, but are not limited to, Green Light Worm Killer, Safer Caterpillar Killer, American Brand Thuricide, and Bonide Thuricide. If there has been an infestation of oleander caterpillars this year, make a note on next year’s calendar to check for young caterpillars in early summer.  Larger caterpillars will require a more toxic pesticide for control, such as carbaryl (Sevin 50WP) or cyfluthrin (Bayer Advanced Garden Multi-Insect Killer). As with all pesticides, read and follow all label instructions and precautions.

For more information on growing oleander, see HGIC 1079, Oleander.

Millie Davenport
Home & Garden Information Center

Page maintained by: Home & Garden Information Center

This information is supplied with the understanding that no discrimination is intended and no endorsement by the Clemson University Cooperative Extension Service is implied. All recommendations are for South Carolina conditions and may not apply to other areas. Use pesticides only according to the directions on the label. All recommendations for pesticide use are for South Carolina only and were legal at the time of publication, but the status of registration and use patterns are subject to change by action of state and federal regulatory agencies. Follow all directions, precautions and restrictions that are listed.