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

It’s a classic cop routine:

• Step 1: do some violence
• Step 2: realize it looks kinda bad, look around and arrest somebody else for what they just did
• Step 3: profit (time and a half for their trouble)