Summary: The Saddleback caterpillar is not just a very colorful creature that feeds on your plants and trees, Saddleback caterpillars can actually be harmful to humans.
Saddleback caterpillars shoot poison through their hairs in self defense. They have stinging horns on each end of their bodies, but the rest of their bodies also have groups of smaller stingers. These stingers are hollow and are connected to poison sacs that fill the stingers with poison on contact, causing them to be painful little pests that should be avoided.
The saddleback caterpillar is unique in appearance. These slug caterpillars appear to have two heads, one on each end, and an eye in the
center of their dark purple-brown backs. The eye consists of a large dark purple-brown oval with a thin white border in a block of green. The green rectangle gives the illusion of a saddle blanket, giving them the name “saddleback”.
The saddleback caterpillar feeds off of trees and shrubs across Eastern North America. Some common trees that they like to feed from are dogwood, elm, maple, and oak, as well as fruit baring trees like apple and citrus trees. They are solitary, like most caterpillars. Most likely the caterpillars are so far dispersed that the damage caused would be minimal. They are not picky eaters and do not have a particular plant on which they prefer to feed. Since the damage is so wide spread among many different varieties of trees and bushes, spraying pesticides is usually not efficient or helpful.
Saddleback caterpillar moths are not as commonly known as the caterpillars because they are not harmful to humans. In fact, few would even guess that the moths and the caterpillars are the same species because of their vastly different coloring. The moth is dark brown with only a little white coloring. This helps to protect them from predators in the exact opposite way as the caterpillars. The moths can easily camouflage themselves in a pile of leaves or up against the bark of a tree.
Saddleback caterpillars loudly proclaim that they are poisonous with their bright vivid coloring. Predators learn that caterpillars with this kind of pattern are harmful to them, and they avoid them. Saddleback caterpillars also try to baffle their enemies. Their "two heads" can cause confusion. Predators don’t know which end to attack.
The Saddleback caterpillar’s colorful patterns and unusual look might make them tempting to pick up and examine from a closer view, but their sting is similar in feeling and intensity to that of a bee or a wasp. Even though they are only about an inch long, the poison from their stingers can be painful to humans for several days. The pain from the sting might be accompanied by a rash and swelling and even sick feelings. These caterpillars are clearly a species to avoid, so never try to pick up one of these caterpillars or even to touch them. Even the slightest brush up against one or trying to flick one of these pests off of a leaf can sting you, causing intense pain.
Use an object such as a stick if you need to remove one of these caterpillars from a plant or from your body. Heavy leather gloves are another option, but use caution. Children may also be tempted to pick up this caterpillar and play with it, so warn them to stay away from all colorful fuzzy caterpillars (no matter how fun they might look) because it is difficult to tell which are poisonous and which are harmless.
If you are stung by a saddleback caterpillar, apply strips of scotch tape to the area, pulling it off carefully to remove stinging hairs. Washing the affected area can help to remove poison. To reduce swelling and numb the stinging sensations, apply an ice pack. A hydrocortisone cream can reduce pain and quicken healing. A baking soda and water paste can also help reduce pain.