CAIRO — First came the lightning that strobe-lit the Nile skies a pale purply gray. What happened next checked all the boxes for a fierce storm: Heavy rain, thunder and flash flooding that sent people scurrying for dry land and crumbled mud-brick houses around Aswan, the largest city in southern Egypt.

Then came the scorpions.

There were hundreds, if not thousands, yellowish four-inchers with as many as six pairs of eyes and a tail full of venom so toxic that the species is known, unscientifically, as the deathstalker.

Swept from their desert burrows by the rains, they came skittering into mountainside villages and burst into homes through cracks in the walls, stinging at least 503 people Friday night alone, according to local officials.

“The floods in the villages of Aswan forced the scorpions out of their hideouts, and they stung some people,” the administrator of a Facebook page dedicated to community news, Nubia, lamented after the waters had subsided. “O Allah, protect the land.”

In the final analysis, the storm that detonated over Aswan with biblical fury at about 9.30pm on Friday inflicted its worst damage with flooding: Three people died, and local officials said 103 homes were partly or fully destroyed, though residents said the real toll was far greater.

On Monday, thousands of people were still doubling up with neighbors or sleeping outside as they tried to salvage whatever they could from the rubble. In a show of discontent rare for Egypt, where most dissent is suppressed by security forces, roughly a dozen protesters demonstrated in front of the Aswan governor’s office Monday over the lack of electricity, water or any government assistance.

But it was the plague of scorpions that turned heads far from Aswan, a few hours south of the ancient temples of Luxor, where the Nile-side pace of life is nonchalant, the small pastel-painted villages ramshackle and the weather dry — until Friday night.

With its vast deserts, Egypt is normally heaven for scorpions, 24 species in all, which make their homes in desert burrows or under rocks and can survive for weeks on end with no food or water. They are such longtime inhabitants of the country that two ancient kings borrowed their names, and the ancient goddess Isis was said to have escaped danger with the help of seven scorpions, who also took the form of a goddess, Serket, in Egyptian mythology.

Friday’s heavy rains proved a less hospitable environment than usual. Scorpion experts said the flooding in Aswan had probably driven them from the mountainous desert that surrounds the area and into the villages.

Deathstalker scorpions — or, as they are known to scientists, Leiurus quinquestriatus — are part of daily life for Aswanis, especially in the summer, when scorpions tend to be more active. They scamper the streets, lurk under stones and trespass homes, nestling in shoes and beneath blankets.

Dozens of scorpion stings are reported in the area each year. If stung, everyone knows, a trip to the hospital for a shot of anti-venom and a few days’ recovery will take care of it.

“We’re just used to it,” said Mr Islam Mohamed, who pilots one of the many small boats that drift down the Nile around Aswan, ferrying people from place to place. “We just hit them with something when we see them.”

Still, 503 stings in one night is unheard-of. Hospitals around Aswan were forced to dig into their anti-venom stashes, and a Health Ministry graphic circulating on Facebook over the weekend warned of the most common symptoms of scorpion stings: Severe pain at the sting site, high fever, sweating, vomiting and diarrhoea.

A deathstalker’s sting can kill a child. Adults may also sicken and die, depending on their health and weight, said Dr Mohamed Abdel-Rahman, a molecular toxicology professor at Suez Canal University who studies scorpion venom.

News reports initially said three people had been fatally stung, but residents said the deceased were three soldiers at a police camp who had been electrocuted in the flooding from fallen wires.

Aswanis said that the rains had been the heaviest in seven years, but that flooding had rarely, if ever, touched residential areas before. The storm’s intensity led some Egyptian meteorologists and scientists to speculate publicly that it was connected to climate change, which has hurt Egypt’s olive and date harvests, turned vast swaths of farmland into desert and made the country’s already blazing summers even hotter.

Mr Mourad Abazid, 56, a government employee from the low-lying village of Kobaniya, on the Nile’s west bank, said the floods had inundated his house, forcing him and his family to shelter at a mosque. He was now sleeping in the street beside the rubble of their home, while his wife and three children stayed with neighbors.

“Thank God, no one died; we rescued people, but our houses are gone,” he said. “We don’t know what we’re going to do now.”

Most houses in the village were at least partly damaged, he said, with some in danger of collapsing. There had been no electricity or water since Friday night.

“It was just an hour of rain, but it wrecked everything,” Mr Mohamed said.

Aswan and the broader region of Upper Egypt have a long history of suffering official neglect. Amid widespread poverty, some Aswanis have turned to freelancing as scorpion hunters, a profitable if risky pursuit.

Scorpions can be milked for their venom, used for scientific research and some medical treatments. A single gram of scorpion venom, requiring the milking of as many as 3,000 scorpions, can be exported for US$8,000, said Dr Abdel-Rahman, who studies medical and scientific uses for the venom.

Toxins isolated from deathstalker venom are used in laboratory research and in cancer treatment, where they can be used to paint tumor cells in the brain during surgery, highlighting them for removal.

“I’m very, very sad when people kill scorpions,” Dr Abdel-Rahman said, “because the venom of scorpions is very rich and useful.”

He and his research team regularly capture scorpions in the deserts around Aswan, Luxor, the Sinai Desert and Egypt’s Mediterranean coast, then stimulate the scorpions with an electrical current to extract the venom. Once milked, the scorpions are released.

In 20 years of scorpion research, he said he had never been stung, a record he credited partly to diligent use of forceps — never his hands — to pick them up by their tails.

“Professionals can catch the scorpions from the tail by hand,” he said. “But I don’t recommend doing that.”

This article originally appeared in The New York Times.