Wikipedia k tomuto pise: http://en.wikipedia.org/wiki/Harvestman#Behavior

Many species of harvestmen easily tolerate members of their own species, with aggregations of many individuals often found at protected sites near water. These aggregations may number 200 animals in the Laniatores, but more than 70,000 in certain Eupnoi. This behavior is likely a strategy against climatic odds, but also against predators, combining the effect of scent secretions, and reducing the probability of any particular individual of being eaten.[2]