Get breaking news alerts and special reports. The news and stories that matter, delivered weekday mornings.

What’s red, clingy (by the thousands) and constitutes the latest menace confronting survivors of Hurricane Harvey?

Fire ants.

They sting. They’re venomous. And they're looking for any dry place — from rescue boat, to backpack, to pant leg — to set up new housekeeping.

The tiny creatures link together in colonies of as many as 100,000 to survive threats like floods. Many giant floating nests have been spotted around Houston and surrounding communities; the latest safety concern in the vast flood-zone left behind by Hurricane Harvey.

The insects effectively form life rafts, with those on the outer layers creating an almost air-tight hull, to ferry thousands of their fellow ants to safe, dry landing areas.

But if the creatures are disturbed (think thousands of human evacuees stumbling away from flooded homes and businesses) the result can be unpleasant and potentially dangerous. The bugs are known to sting en masse — a particularly worrisome outcome for anyone allergic to their alkaloid venom.

Let our news meet your inbox. The news and stories that matters, delivered weekday mornings. This site is protected by recaptcha

Most people just feel a burning sensation and are left with a red patch of skin, but an allergic reaction can trigger anaphylactic shock, which can include welts and trouble breathing.

Journalists and many others have been posting pictures of massive floating ant colonies found around Houston and other communities. Some colonies, bunching together, cover multiple square feet of open water. Others are smaller and more tightly bunched.

Meanwhile, in Cuero, the river has brought my aunt all of the fire ants. Yes, those are all (of the) fire ants. pic.twitter.com/dEibWYxAdl — Bill O'Zimmermann (@The_Reliant) August 29, 2017

There have been no public reports of flood victims suffering fire ant attacks as of midday Tuesday. A nurse at the Texas Medical Center in Houston said Tuesday she knew of no patients who had been treated. But experts says the ant flotillas can remain intact for extended periods, as the creatures wait to find a dry haven to re-establish their colonies.

Still, the presence of the thoroughly-detested creatures had Houstonians wondering when their ordeal would be over and even invoking the Book of Revelation.

Pro tip: Don't touch the floating fire ant colonies. They will ruin your day. #Harvey pic.twitter.com/uwJd0rA7qB — Mike Hixenbaugh (@Mike_Hixenbaugh) August 27, 2017

Houston Chronicle medical reporter Mike Hixenbaugh tweeted that the colonies were “everywhere,” as he posted a video of a large ant-flotilla and advised: “Pro tip: Don't touch the floating fire ant colonies. They will ruin your day. #Harvey Yes, flotillas of fire ants are a real thing that happens in Houston — and elsewhere — when it floods.”

Others reported via social media that stranded fire ants had been known to crawl up oars to land on boats.

Floating fire ant colonies in the floodwaters in Houston on Aug. 29, 2017. Mike Hixenbaugh / Houston Chronicle via Twitter

Scientists have written multiple papers on how the ant colonies bond together to save themselves during calamities like floods. They link themselves together to form an almost water-tight bond, with the queen and larvae protected in an inner chamber.

And some experts have said that the fire ant is one of many species that appears to be thriving in the warmer temperatures globally that have come with climate change. One model shows the warmth-loving pests, native to South America but imported in the last century, expanding their range by more than 20 percent and spreading as far north as Nebraska, Kentucky and Maryland by the turn of the century.

The water-borne flotillas are not unlike swarms of bees, which bunch tightly when they leave one hive to form another. The bees hang from any manner of objects, often tree limbs. The queen is protected inside the mass of insects, tended by “nurse” bees that keep her clean and fed.

Lest there be any doubt about what misery fire ants can unleash, just talk to a victim. Eric Westpheling, now a cinematographer in New York City, recalls an encounter when he was visiting his parents home near Lake Travis, when the Texas lake was at historic high levels.

He stepped on a ball of ants, which stung him multiple times. "It got nearly incapacitating quite quickly," said Westpheling, now 33. "And I had to have my girlfriend drive me back to the house ASAP and help me with water and pills."

He called the encounter, more than a decade ago, "very intense" and said the realization that "angry ants can float put me off swimming there for a few years." Westpheling concluded: "Praying for Houston folks."

Houstonia magazine tried to take (a bit) of a lighter view in its article warning residents to be on guard. "Bless them," it wrote. "They’re just trying to make it, like the rest of us. Even if they’re horrible little ankle-biters."