Scientist sees no signs yet of rise in caterpillar population

Advocate staff photo by HILARY SCHEINUK -- Recently hatched buck moth caterpillars are seen on an oak tree in Baton Rouge on April 20. Many south Louisiana residents come in contact with these stinging insects every spring. The caterpillar's spines are hollow and connected to poison glands, and contact with them can cause a painful sting coupled with inflammation similar to a bee sting. The irritation can last several days and can be accompanied by nausea. Show caption
Advocate staff photo by HILARY SCHEINUK -- Recently hatched buck moth caterpillars are seen on an oak tree in Baton Rouge on April 20. Many south Louisiana residents come in contact with these stinging insects every spring. The caterpillar's spines are hollow and connected to poison glands, and contact with them can cause a painful sting coupled with inflammation similar to a bee sting. The irritation can last several days and can be accompanied by nausea.

People who talk about the joys of spring may have never felt the big sting of a tiny caterpillar that appears in south Louisiana when the weather warms up.

The culprit is the buck moth caterpillar, and an LSU Agricultural Center entomologist said the sting from the red-and-black caterpillar is worse than those of the other well-known stinging insects: bees and wasps.

“It really does hurt,” Dennis Ring said. “People brush up against trees or the larva falls on them and they get stung.”

Ring said he’s seen no signs of an increased buck moth caterpillar population this year, but there could still be more crawling in the trees than normal.

The black and white buck moth lays eggs during the winter mostly in oak trees in southern states from Texas to Florida and up the eastern coast to the northeastern part of the nation.

The eggs begin to hatch in March and April.

Once the caterpillar leaves the egg, it feeds for about 30 days — which is when people get stung — and crawls to a place where it can go into the pupa stage, usually in the ground, and eventually transforms into a moth — Hemileuca maia — a few months after pupating, Ring said.

The cycle then begins all over again.

The caterpillar’s poison is not enough to cause a person to seek immediate medical attention, Ring said, but there are exceptions.

“If you have a severe allergic reaction, you’d want to go to a hospital, but otherwise I wouldn’t say go to the hospital,” Ring said. “If you get stung by a whole slew of them, then you might seek medical attention.”

The poison is transmitted through what are called “urticating hairs,” which resemble stingers that Ring likens to glass tubes that break off in the skin, allowing the poison to get into a person’s system.

Ring said it causes a spot on the skin that can stay visible for several days and has been known to cause nausea.

The best way to treat stings, Ring said, is to repeatedly place clear tape on the affected area and peel it off until the urticating hairs come out, then place baking soda, meat tenderizer, tobacco or toothpaste to counteract the poison.

The best way to get rid of the caterpillars if they are becoming a problem is to use an insecticide that contains Bacillus thuringiensis as the active ingredient, Ring said. He said the bacteria will only be harmful to moths and butterflies, not other insects.