DDT doesn't run the risk of "running away" out of control the way biological/bacterial/viral interventions do. This is my first time hearing about screwworm and 1) wow what a nasty looking infection, and 2) boy am I glad it looks like the eradication campaign is going well! And yes the screwworm program does seem really similar to this, so especially thrilled it seems to be going well!

Afaik, DDT continues to be accepted for malarial mosquito control; DDT as an agricultural pesticide is what got a worldwide ban.

Well, widespread spraying with DDT did essentially create a permanent reservoir of DDT-resistant mosquitoes, which also made them resistant to pyrethroids. Bit of a problem. Fun fact - DDT makes spider mites extra fertile.

I do agree however that the eradication efforts of both caused significantly more good than harm, no question.