Not 100% sure what you’re asking, but if you are asking what I think you are asking:
Infested Carriers show up in drone space anoms. Once they spawn, they’ll warp between sites and belts if the site they spawn in is empty (such as when you lose your 'snake, or if you warp out in time).
Given that you’re using auto-targeting missiles, I’d assume you were ratting semi-AFK. Probably not smart in a ~2bil ship.