https://en.wikipedia.org/wiki/Cochliomyia

Note this distinction:

Unlike most other maggots, these maggots attack and consume healthy living tissue along with decaying tissue (hominivorax literally translates to "man-eating")

The "primary" screwworm, which can pierce skin, causes most livestock damage and is the focus of the eradication effort. Versus

The secondary screwworm, C. macellaria, is a flesh-eating fly whose larvae consume only necrotic tissue, either that of carrion or of an animal or human host (myiasis). This important distinction between C. macellaria and C. hominivorax was not understood for much of medical history; myiasis of humans and animals was viewed as universally disastrous. However, as medical understanding of the process of tissue breakdown and infection progressed, it was observed that wounds with specific types of maggot infestation actually had a decreased severity and duration of infection. This progressed to the point where C. macellaria larvae were being applied in some cases as surgical maggots. However, the negative connotation surrounding the word “screwworm” has persisted, and the largely harmless secondary screwworms are often blamed for myiasitic attacks for which primary screwworms are actually responsible.

As often, success of an eradication program depends on staying the course.