By Kelli Dugan
MOBILE, Ala (Reuters) - They swarm. They eat. They die.
The average one-year life span of the eastern lubber might seem lackluster, but the distinctive black grasshopper relatives make quite a splash as they gorge their way in locust-like clouds across the Southeast.
Marion Humphreys, 54, wasn't prepared for what he witnessed on a recent Sunday in downtown Mobile, Alabama.
"Man, I didn't know what was going on. It was like some kind of plague," Humphreys said.
"They're big and creepy looking, and they were just everywhere. I thought I was seeing things at first, but then you could see them moving across the street in one big blob."
The lubber invasion in southern Alabama has reached its annual peak, with four-inch lubbers -- still in their nymph stage -- feasting on ornamental plants such as lilies and irises.
The insects' bright red and yellow markings stand in stark contrast to their black bodies. As they mature into adults, lubbers can exceed six inches in length and typically turn a yellowish color with black markings.
The curious creatures tend to congregate based on food supply in the same places year after year, said Bill Finch, director of the Mobile Botanical Gardens and former conservation director for the Alabama chapter of the Nature Conservancy.
Eastern lubbers tend to prefer open pine woods, weedy fields and heavily vegetated roadsides, usually along drainage ditches, according to University of Florida researchers.
But Finch said it's also not uncommon to find them attempting to navigate urban areas where such vegetation is available, he said.
"They're very heavy, and they don't fly. Fortunately, they don't make an appearance here," he said of the botanical gardens.
Shonda Borden, assistant manager at 5 Rivers Delta Resource Center in Spanish Fort, Alabama, and an entomology enthusiast, is fascinated by the lubbers' myriad defense mechanisms.
"If you paddle out, you'll see them clinging to the tall marsh grasses, and you'd think that these boldly colored, four-inch insects just hanging out in the wide open would make a very good meal for birds, but you'd be wrong," she said.
"They might look like they'd be easily picked off, but these guys are toxic and their bright coloring is a warning to birds and other larger bugs to back off," Borden said.
The lubbers' diets render them poisonous to predators, and it is not unusual for unsuspecting diners like raccoons to vomit their snacks back up or even die if they consume too much of the poison, Borden said.
But Borden said one species, a bird known as the loggerhead shrike, has found a way around the lubbers' poison.
"The shrikes will impale their food on a twig or a branch or even a barbed-wire fence, and then come back for them later. The idea is that the poison in a lubber's system breaks down once it dies, so when the bird returns, it's safe," she said.
Lubbers spread their wings, hiss, secrete a foul-smelling froth and even expel a fine spray of toxic chemicals as far as six inches when they're alarmed or feel threatened, according to Douglas Whitman, an Illinois State University biology professor and insect curator.
Should tenacious predators persist, lubbers have also been known to vomit up their last meal in an attempt to make the predator lose its appetite, Borden said.
She said Louisiana natives have adopted their own pet name for the peculiar pests.
"They call them 'devil's horses,' and I guess they do look sort of fierce in a small, grasshoppy kind of way," Borden said.
(Editing by Colleen Jenkins and Jerry Norton)