Vertigos

The Vertigos are Leto-born creatures who can travel accross the lands without fearing the sun, since they evolve under the snow like earthworms.

They have a sort of "bulb" of Leto and their main goal is to blow it inside some creature foot. The creature, whether it is human or not, will spray Leto roots at each step it makes, creating Leto forests some months later.

They do so by biting the creature foot ; some bitings hurt a lot, other don't at all, since grown up Vertigos devellop an serum that acts as an anesthesys. Some Vertigos devellop enough strenght and intelligence to bite car heels so the travellers are stuck in an infected area.

The vertigos are attracted by crops and all kinds of agriculture fields. That is why it is dangerous to cross a field in no-return and also why underground crops, alimented by UV, are taken care by people wearing high security boots.

When somebody is infected, he is immediatly put in quarantine and has his leg automatically cut off. His travels are studied and teams are sent to locate the infected areas, evacuate them and burn them if it's not too late. If it is, a wall is built, surrounding the place and the people who lived in are not allowed to go back to their homes.