New communal roosting tradition established through experimental translocation in a Neotropical harvestman

► We found that harvestmen have roosted communally in the same sites for 10 years. ► Site characteristics predicted the size, but not the location, of the aggregations. ► These appear to be traditional roosts maintained by chemical conspecific attraction. ► We established a new communal roost simply by translocating animals to new sites. ► Our findings may be relevant for conserving species that roost communally.