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Thursday, June 11, 2009

Oleander Caterpillar

You might be surprised to learn that those colorful little wasp-like moths that frequently enter your butterfly garden are responsible for those hairy orange caterpillars that can defoliate an oleander shrub or desert rose in a flash.

The adult stage of the oleander caterpillar, Syntomeida epilais Walker, also known as the Uncle Sam moth or polka-dot wasp moth, is small and iridescent blue/green with a reddish abdomen and small white dots. It is active in the daytime, flying slowly from flower to flower.

Just before sunrise, and after an ultrasonic courtship, the female deposits her pale yellow eggs on the underside of oleander and desert rose leaves. Young larvae are gregarious and feed together, turning new shoots light brown. As they mature, they become more solitary and consume whole leaves. Oleander and Gulf Fritillary caterpillars look alike with orange bodies. The way to tell them apart is by the black protrusions, spike on a Gulf Fritillary caterpillar and brushes on a Oleander caterpillar. Neither caterpillar are considered to be a stinging hair caterpillar.

Oleander caterpillars will not kill plants but they can cause unsightly damage. The best time to control these pests is when they are young and feeding in groups so that infested foliage can be easily removed. Seal the cuttings in a plastic bag and freeze to kill the larvae. Be sure to wash your hands thoroughly to remove the poisonous oleander sap. Larger, solitary caterpillars can be removed by hand and then frozen or dropped into a bucket of soapy water.

Since these caterpillars consume the poisonous oleander, birds and small animals do not feed on them. However, these insects are susceptible to various viral, fungal and bacterial diseases, and their natural enemies include predatory stink bugs, parasitic flies and wasps, and fire ants.

A least toxic insecticide, such as Dipel or Thuricide (Bacillus thuringiensis) are recommended as a bacterial stomach poison for the caterpillar chewing the oleander leaves.

For more information:

These links were current as of May 2013.

Article Credits:
Ellen Sculley, UF/IFAS
Kim Gabel, UF/IFAS

Photo Credits: UF/IFAS


Anonymous said...

I found the caterpillars on my Desert Rose plant and sprayed them with a mixture of minced garlic and red pepper mixed with water. They dropped right off. I was concerned that I had killed a beneficial caterpillar.

Anonymous said...

Caterpillars are never considered "beneficial", as all caterpillars feed on leaves and cause foliar damage. They are considered pests if the damage is intensive and causes harm to the plant or if the damage is unsightly. I personally don't care as long as my plants don't die.

Anonymous said...

About 50 of those ate my desert rose over night and started eating a corn palm too. i tried killing them with a natural pesticide I had then got nervous because they were so many so I got out he big guns and downed them. They literally ate the leaves and flowers off the whole plant over night. scared me so bad i thought they would eat the whole yard by morning

Anonymous said...

Who is the person who said that caterpillars are never "beneficial"? They ALL turn into moths or butterflies which are beneficial -- so lets kill all the caterpillars and therefore there will be no more moths and butterflies on the earth! Geezz...

Anonymous said...

I have two caterpillars - yellow with silver dots feeding on two of my Desert Rose plants. I've raised butterflies, but never saw these caterpillars before. I am collecting Desert Rose plants - had no idea they would be eaten. Can I move these to another plant. It's midnight, just went out and picked 3 off my roses with leaves. What now?

Anonymous said...

I attend college in South Florida. My roomie was surprised to find Uncle Sam and his brothers on her Yellow Mandevillas. So we transported them to our school property's plant. We also kept Uncle Sammy. I am appalled that y'all want to kill Uncle Sam and his brothers by freezing them to death. I think we should just transport them to someone else's plants. That way they can still live a hearty life. Shalom.

dawn soleri said...

The bugs turn into ugly moth-like creatures. Just spray thyme or tea tree essential oil diluted in some water. I srayed this morning, and as the sun comes out, the caterpillars are dropping off the plant and dying.

Anonymous said...

I think this caterpillar fell on my toe and although it didn't hurt days later I have this rash my toe