It's just before dawn in Piracicaba, a small city in southeastern Brazil, when a large white van pulls over to the side of the road. A door slides open, revealing stacks of crates jammed with plastic pots. Each pot is buzzing with mosquitoes.
"There's about 1,000 mosquitoes in each of those pots," says Guilherme Trivellato, who works for Oxitec, a biotech company that owns the van. All together, there are more than 300,000 mosquitoes swarming inside those pots.
"That's how many we're going to release today," he says.