Dispersal by swarming in a social spider.

Groups of Achaearanea wau (Theridiidae) disperse and found new colonies by means of synchronized emigrations of adult and subadult females. Emigrations involve the construction of silk highways from parent colonies to new web sites, synchronized migrations along the highways, and the establishment of daughter colonies. Emigrations of Achaearanea wau are similar in timing, group composition, and in some behavior components to swarming of social bees and wasps.