The inch-long saddleback caterpillar looks like it has two heads with spiky features at both ends. Its primary color is reddish brown. But it has a chartreuse and white “blanket” over its midsection with a reddish brown oval “saddle” straddling the top.
“It is reputed by many experts to be the most dangerous caterpillar in North America,” said Tim Schowalter, LSU AgCenter entomologist and head of the Department of Entomology, adding that people must use extreme caution if they see one.
Schowalter says stings can be treated by putting adhesive tape over the stung area repeatedly to remove any spine tips. Use a fresh strip of tape each time. Then thoroughly wash the area with soap and water to help remove irritating venom.
“Prompt application of an ice pack and a baking soda poultice can help reduce pain and swelling,” he said. “Oral or topical antihistamines may help relieve itching and burning.”
These caterpillars can be encountered on a variety of host plants, including oak, maple, willow, apple, aster, blueberry, buttonbush, citrus and corn.
“They appear to be more common than usual in the South this year,” Schowalter said. “Even so, their numbers probably do not warrant insecticide application.”
Schowalter says be on the lookout for the saddleback caterpillar. Avoid it. If you see one, try to carefully remove and destroy.
The second is the fall webworm, a pale tan-yellow caterpillar that can be anywhere from a half inch to 1.5 inches in length.
“Despite its name, it is common now in Louisiana,” Schowalter said.
The caterpillars’ silk tents are conspicuous on a variety of forest, fruit and ornamental trees. Damage is usually restricted to a few branches, but this can be serious for small fruit or ornamental trees.
Schowalter says these caterpillars can be controlled by clipping and removing the affected branch or spraying with Confirm 2F, Dylox 80% SP, Spintor 2 (spinosad), Malathion 57% EC and Methoxychlor 50WP at labeled rates.
Dale Pollet, retired extension entomologist, says the spinosad formulation will work on these caterpillars and is safer for homeowners.