This topic always leads me back to reading about the Darién Gap [0]. When eradication was working successfully, they had managed to push the screwworm population all the way back to the Gap and keep it out of major population/agriculture areas. There were (or are) yearly efforts to perform the sterile insect technique [1]. Expensive to perform, but worth it for all the damage they'd otherwise cause if left unchecked.

[0] https://en.wikipedia.org/wiki/Dari%C3%A9n_Gap

[1] https://en.wikipedia.org/wiki/Sterile_insect_technique