I usually run Rimworld with a handful of events (Planetkiller, Heat Wave and a few others) disabled.

Does having Heat Wave disabled prevent Teostra/Lunastra from spawning, or does them showing up create a heatwave by virtue of them being present at all? I don't mind having to kill them to end one, but if I have to turn heat waves on in order to encounter them at all I'd rather do that earlier than later y'know?