SAN QUINTIN, Mexico (Reuters) - Huddled around a single flickering candle in a tiny wood and cardboard shack on scrubland in Mexico's northwest, labourer Genaro Perfecto and his family prepared to bed down for the night on a bare earth floor.
His 3-year-old daughter asked for an extra blanket to ward off the cold, but they had run out - a measure of their hard-scrabble life spent harvesting fruit bound for U.S. dining tables.
Since March, thousands of day labourers have blocked roads, staged marches and held meetings with lawmakers to protest the grind of picking strawberries, raspberries and blackberries in the Baja California peninsula for what they say is as little as $1 (63p) an hour.
Perfecto is part of a growing underclass whose frustration over pay and conditions is pressuring companies that supply U.S. markets to make improvements.
At least one company told Reuters it would reexamine its treatment of workers.
Kevin Murphy, CEO of U.S. fruit company Driscoll's, said his company was reevaluating standards in the wake of the fruit picker protests, and was going to audit living conditions.
"We're going to go back and look at them again and reevaluate them and put in some improvements," Murphy said.
Companies operating in the area say they pay workers fair wages and provide them with adequate healthcare coverage. Local government officials, meanwhile, say recent protests over wages by fruit pickers were politically motivated.
Having moved north to escape poverty in southern Mexico 15 years ago, Perfecto, a father of five, said he is too poor to simply move away from this dusty stretch of industrial farmland known as San Quintin.
"If you're ill, or cut yourself in the fields, they don't pay the day (if you are out for treatment)," he said, flanked by plastic bags dangling from the low roof that serve as storage for their belongings, a few threadbare clothes and blankets.
"You keep quiet, and keep working covered in blood," added Perfecto, a 38-year-old whose main diet consists of refried beans or flour tortillas sprinkled with salt.
Perfecto works for Mexican firm BerryMex, a major supplier for Driscoll's. A BerryMex representative said it pays workers on a regular contract even if they are sick. But the representative also said temporary workers, who make up about 75 percent of its workforce, are not paid for fruit they have not picked.
In the last few months, labourers have expressed increasing anger over conditions that even some conservative Mexican media have characterized as "near slavery".
On March 18, more than 200 protesting workers on the peninsula were arrested in a clash with local authorities. Several protestors were injured on Saturday in fresh disturbances.
The boom in sales, meanwhile, has enabled fruit companies to pay above the minimum wage, which in Mexico is 70.1 pesos ($4.57) a day.
On average, Perfecto picks around 110 kg (243 lbs) of strawberries a day, and up to 200 kg (440 lbs) in high season, he said. Across the border in the United States, a kilo of strawberries fetched $5.19 on average in 2013, according to U.S. government data.
But Perfecto said he earns between 850 and 1,200 pesos ($56-$79) in a week that regularly exceeds 50 hours, roughly between $1 and $2 an hour.
Five of some three dozen workers interviewed by Reuters showed payslips reflecting earnings of between 782 pesos ($51.10) and 1,210 pesos ($78.80) per week. The slips did not provide a clear breakdown of the hourly compensation.
When asked how much it paid per kilo, a BerryMex representative stated only that workers had an "average earning opportunity" of $5 to $9 an hour with top workers making up to $10 per hour.
This, BerryMex added, resulted in average weekly earnings of 3,600-7,200 pesos ($238-$476) in a 48-hour week.
A company representative could not account for the gap in the wages the company cited and those reported by workers.
"Where we find something that is wrong, we will correct it. No one is perfect in this world," said Hector Lujan, CEO of BerryMex.
Among the labourers hauling heavy crates packed with strawberries was Carmen Reyes, 34, who is seven months pregnant.
Reyes says she will keep working as long as possible before giving birth in order to keep making money, as she has done during her previous nine pregnancies. One of the children died at 2 months.
Like Perfecto, she lives in a makeshift shelter made from cardboard and plastic sheeting, and complains of rashes and skin discoloration from her work in the fields.
"When we're nearby cutting fruit, they don't care, they continue to fumigate" with pesticides, she said, gesturing to a white patch of skin on her forehead.
Behind Reyes sat one of her daughters, aged 15 and caked in dirt. Outside, her husband, gaunt and dusty, worked on a rudimentary extension to their shack.
"They say it won't harm us, but we think it does," she said.
Editing by Simon Gardner, Dave Graham and Ken Wills