IIRC, there's some parasite that makes the host (some species of insects) climb up plants, as high as possible, so that it can be eaten by birds and other animals.
So that the parasite can reproduce inside the new host, and spread further.
So that the parasite can reproduce inside the new host, and spread further.
What OP is talking about sounds more like the lancet liver fluke, which has a stage of its lifecycle inside an ant and a stage inside a grazing animal, so it makes an infected ant climb to the top of a grass stalk. Amazingly, the ants only do this from dusk till dawn, resuming their normal activities if they haven't been eaten by dawn. The rationale seems to be that being exposed to the hot sun during the day could quickly kill the ant along with its passenger flukes
I think every Chinese person has heard of it since they were kids.