89 points ·
>How screwworms managed to jump the barrier in 2022 is not fully clear. But in the years immediately before, the coronavirus pandemic reportedly created supply-chain snarls at the fly factory in Panama and disrupted regular cattle inspections that might have set off the alarm bells earlier.
>Still, the screwworm advanced relatively slowly through Panama and Costa Rica for the first couple of years.
>800,000 cattle a year are raised illegally in nature reserves [in Central America] and then smuggled by boat and truck up to Mexico. This allowed the screwworm to spread much faster than it can fly [beginning in 2024]. The line of new screwworm cases followed known smuggling routes