A fungus makes house flies climb somewhere high before killing them from inside
Entomophthora muscae infects common house flies, and in its final days takes over the fly's behavior: the dying fly climbs to an elevated, exposed spot, extends its proboscis to glue itself in place, then raises its wings before the fungus bursts through its body to release spores onto whatever's below, ideally more flies. The fungus effectively turns its host into a spore-dispersal tower it builds and operates itself.