It’s that time of year again: tussock moth season.
If you’re in Florida and have ventured outdoors lately anywhere with oak trees, you may have come across a single caterpillar – or hundreds.
The ubiquitous insect suffering its annual epidemic is the fir tussock moth, or Orgyia detrita for those who prefer scientific nomenclature. The creatures, which are abundant statewide, can cause skin irritation, so read them before rounding up or touching them.
“In my experience, it always happens in this part, north-central Florida, at this time of year. Late March and April, we get a lot of these things,” James Hayden said. , a taxonomist with the Department of Agriculture and Consumer Services, Florida Plant Industry Division.
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How to Identify the Caterpillars of the Tussock Moth
Fir tussock moths are found primarily in Florida, as well as the Gulf Coast and some eastern seaboard states.
The two others Orgy species found in Florida are the white tussock moth (Orgyia leucostigma) and the less common definite butterfly (Definitive orgy). Both are present in the eastern United States beyond Florida.
The tussock moth caterpillars are identifiable by their red heads, two black “hair pencils” that look like antennae, a dorsal hair pencil, four prominent yellow or white tufts on their backs, and orange spots all over.
There are two phenotypes, a lighter and a darker. Many have bright yellow hairs, while some have white or off-white hairs.
White tussock moths are similar in appearance but have a lighter body color and yellow spots. Tussocked caterpillars have yellow or tan heads and a pale body.
Why are there so many?
“Oaks are their primary hosts, so if you have oaks in the area, every year at this time of year is a great time for the tussock moth,” said Adam Dale, assistant professor in the department. of entomology and nematology from the university. from the Florida Institute of Food and Agricultural Sciences.
Butterflies overwinter as eggs, which hatch as the weather warms. Most eggs hatch in late March, so late March and early April are peak times to see the caterpillars, which have developed by eating oak leaves and preparing to spin a cocoon and pupate.
The further south and warmer the climate, the sooner they can appear.
“In years like this year when they really seem to have exploded, they’ll fall out of the trees and end up everywhere,” Dale said. “Even in years when they’re not very dense, once the caterpillars are almost done growing, they leave the tree, so they fall off the tree and then climb onto other structures and surfaces like porches. , windows and shutters and anything on your house.
It is difficult to predict the prevalence of caterpillars from year to year, but temperature and precipitation in fall and winter may play a role.
“They have one generation a year, so once the caterpillars are done developing around this time, we won’t be seeing them again until next year this time around, but there are always ups and downs in terms of their abundance in any given year,” Dale mentioned.
Will there be as many butterflies?
Dale and Hayden say you won’t see as many moths as caterpillars when they emerge from their cocoons in mid-April and early May for several reasons.
First of all, caterpillars have predators.
“A lot of things will eat them too,” Dale said. “The predominant things are beetles, birds and wasps, like the paper wasps you would see on the side of your house. These adults are catching caterpillars.
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Second, male brown moths aren’t as showy as caterpillars, and females are hard to spot.
“All three species of Orgyia, the females are entirely wingless, and they look like little balls of gray fluff, like a cute little dustball with a little butterfly head,” Hayden said. “You might be lucky enough to see one sitting on a house calling for a male and then it will fly and they will mate and she will lay the eggs where she is sitting.”
The female will lay eggs on her cocoon and then die.
Are fir tussock moths dangerous?
Cocoons and caterpillars can be irritating to the touch with bare skin.
“On the sixth and seventh abdominal segments right in the middle, you’ll see two orange circles, and those little orange circles are actually glands that produce a defensive secretion,” Hayden said.
Tussock moth caterpillars do not fall into the category of stinging caterpillars like saddleback caterpillars and cat caterpillars, but they do have stinging hairs that can be dangerous if touched, especially the four tufts , or “tufts,” on the back, says Dale.
“It’s the hairs that sting, and if you were to rub them with your skin, it could cause irritation, and that’s what people are worried about,” he said. “There’s a whole range of reactions to it, like some people like me don’t react to it and others may get a rash, a little rash.”
Cocoons are made up of hairs, so they can have the same irritating effect. They are white to tan and fuzzy in appearance, often sticking to the sides of houses and other structures.
What can I do about them?
If the presence of the caterpillars or cocoons is overwhelming, there are a few tactics that can help.
“You can sweep them up in soapy water, or you can vacuum them up with a shop vacuum, basically physically removing them from the situation and disposing of them,” Dale said. “It’s the best thing you can do to get them into your home or places where you don’t want to be exposed to them.”
The cocoons can also be sucked or scraped into a container.
Although homeowners are often concerned about caterpillars defoliating trees, Dale only recommends applying insecticides in extreme or high-risk situations.
“Oak trees are home to all kinds of caterpillars, and it’s just a good food source, but they don’t harm oak trees,” he said. “When you (apply insecticide) you also control all the hundreds of other caterpillars that feed on oak trees, and those support birds and all kinds of other wildlife.”
A justifiable situation might be an oak tree in a day care center or an area frequented by children. However, insecticides applied to the tree won’t do much unless applied in the winter or early spring in anticipation of egg hatch, as the caterpillars have nearly completed their development.
In other words, since the caterpillars will only be in a few weeks, the best option may be to admire them from afar and enjoy the good weather.
“I think they’re really nice little caterpillars,” Dale said. “They’re really cool. I always get excited when I see them just because it means spring is here.
Contact reporter Danielle Johnson at [email protected]
This article originally appeared on Ocala Star-Banner: Tussock moth caterpillars return in abundance to Marion County