gregarious \grih-GAIR-ee-us\, adjective:
1. Tending to form a group with others of the same kind.
2. Seeking and enjoying the company of others.
True locusts, which are actually certain kinds of grasshoppers, are usually solitary and rather sluggish, but when they are crowded they enter a gregarious and highly active migratory phase.
— Gilbert Waldbauer, Millions of Monarchs, Bunches of Beetles