You may see these interesting caterpillars on your palms or pigeon pea plants here in South Florida, although the Io moth caterpillar (Automeris io) feeds on a number of other native plants including the Royal Poinciana and Hibiscus. Those little spines pack a nasty neurotoxin that is extremely painful for a few hours, with another 6-12 hours of discomfort and side effects (nausea, headaches, sleeplessness, etc.). The spines break off easily at a light touch and release the venom into the skin. Apply and then remove tape to remove any spine tips, and apply ice to reduce the inflammatory response.
Eggs hatch into a small rusty brown caterpillar that molts 3 or 4 times before showing the green w/racing stripes. They are painful at all stages, so be careful when removing them. The younger, brown larvae are often seen travelling end to end in a line moving to a new location to feed.
Management involves monitoring, identifying and physical removal. I use long forceps to remove from plants and drop in a container of soapy water to kill them. Continue monitoring closely for a few days making sure you have found them all, being careful not to touch them.
A number of flies and wasps are known parasites of the io moth, laying their eggs under the skin of the larvae. The eggs hatch and the larvae feed on the growing caterpillar, often in white, rice-like “tubes” that develop on the sides of the caterpillar. Eventually the adult wasp or fly emerges from the end of the tube. The second photo shows the larval tubes of a parasitic wasp on an io moth caterpillar, you can see some of the tubes are open where the adult wasp emerged from. Whenever I find these parasitized larvae in my garden I leave them alone, as they die soon after, and the parasitic wasps are harmless to humans and help keep a number of caterpillar pests out of the garden.
